Calcified coronary lesions

Summary

Heavily calcified vessels represent a challenge for percutaneous coronary intervention (PCI), as they might be associated with stent delivery failure and suboptimal deployment. The mechanisms of vascular calcification are now recognised as complex and highly regulated processes that involve activation of cellular signalling pathways, circulating inhibitors of calcification, genetic factors, and hormones[11. Leopold JA. Vascular calcification: Mechanisms of vascular smooth muscle cell calcification. Trends Cardiovasc Med [Internet]. 2015 May;25(4):267–74. ]. To date there are no established interventions to prevent coronary calcification. There are, however, some therapeutic tools which enable PCI in calcified vessels, and these are the focus of this chapter.

Mechanical debulking of atherosclerotic plaques with rotational atherectomy prior to stent placement was originally proposed as a viable strategy to allow PCI in heavily calcified lesions and other challenging lesion settings such as ostial stenosis, diffusely diseased vessels, and chronic total occlusion. Clinical trials have failed to show an improved mortality or even a reduced rate of repeat target lesion revascularisation with mechanical debulking over conventional PCI, thus, in the past, limiting the widespread use of this technique. DES have, however, significantly reduced clinical restenosis (to less than 10% in most cases) and have hence expanded the indication for PCI to lesions and anatomical settings previously not attempted. As a result, there has been a resurgence of interest in plaque modifying tools over the last 5 to 10 years, as well as recent development of new technologies and improvements to older technologies.

Contemporary single-centre registries demonstrate a favourable clinical outcome and low repeat revascularisation rates, even with heavily calcified lesions, after adequate plaque modification. This, together with an ageing population demographic, has resulted in increased PCI in heavily calcified coronary lesions using tools no longer seen as for debulking but rather as tools to enable optimal DES delivery and deployment in extremely challenging lesions.

Introduction

Nearly all patients with cardiovascular disease have some degree of calcification, and, in asymptomatic adults, prevalence of coronary calcification corresponds roughly with age. Among 60-year-olds, approximately 60% have calcific vasculopathy. The diagnosis of moderate to severe calcification is increasing as techniques for detecting coronary calcification improve. Recent registries and meta-analyses estimate a prevalence of 18 to 26%, with the most-extensive vascular calcification occurring in patients with chronic kidney disease, type II diabetes mellitus, advanced age, systemic hypertension, and dyslipidaemia [22. Budoff MJ, Shaw LJ, Liu ST, Weinstein SR, Mosler TP, Tseng PH, et al. Long-term prognosis associated with coronary calcification: observations from a registry of 25,253 patients. J Am Coll Cardiol [Internet]. 2007 May 8;49(18):1860–70. ][33. Moe SM, Chen NX. Pathophysiology of vascular calcification in chronic kidney disease. Circ Res [Internet]. 2004 Sep 17;95(6):560–7. ][44. Shao J-S, Cheng S-L, Sadhu J, Towler DA. Inflammation and the osteogenic regulation of vascular calcification: a review and perspective. Hypertens (Dallas, Tex 1979) [Internet]. 2010 Mar;55(3):579–92. ][55. Copeland-Halperin RS, Baber U, Aquino M, Rajamanickam A, Roy S, Hasan C, et al. Prevalence, correlates, and impact of coronary calcification on adverse events following PCI with newer-generation DES: Findings from a large multiethnic registry. Catheter Cardiovasc Interv [Internet]. 2018;91(5):859–66. ].

Pathophysiology of vascular calcification

Vascular calcification can be located in the intima (within atherosclerotic plaque) or in the media (within the medial smooth muscle layer). The histological appearance of calcification can be amorphous (lacking tissue architecture) or chondro-osseous (having the tissue architecture of cartilage or even bone). Medial calcium is more often circumferential owing to its association with elastic tissue. Vascular calcium deposits can resemble bone from a macroscale to a nanoscale level.

Peripheral arteries tend to have predominantly medial calcification. The calcification process is potentiated by various predisposing factors such as hypercalcaemia, high serum phosphate and elevated parathyroid hormone, which promote activity of osteoblast-like cells in the media to form calcification.

The mechanism of atherosclerotic coronary calcification differs, in that dysmorphic calcium development is driven by chondrocyte-like cells, in a process which is directly related to the inflammatory milieu that is created by endothelial dysfunction and atherosclerotic plaque development. There is interplay between death of inflammatory cells, smooth muscle cell debris from apoptosis, and lipid-laden macrophage-derived matrix vesicles within coronary atheroma which promote calcium phosphate crystal formation. Cholesterol deposits under the endothelium initiate an intense inflammatory response that causes the development of microcalcification, while the differentiation of vascular smooth muscle cells and pericytes promote the deposition of bone as part of the necrotic core of atheroma. A lack of calcification inhibitory factors such as matrix gamma-carboxyglutamic acid protein, osteopontin, osteoprotegerin and feutin-A further disrupts the balance of osteogenic and osteoclastic mechanisms. These pathophysiological and mechanistic pathways provide potential preventative or reversal targets for future medical therapies [66. Nakahara T, Dweck MR, Narula N, Pisapia D, Narula J, Strauss HW. Coronary Artery Calcification: From Mechanism to Molecular Imaging. JACC Cardiovasc Imaging [Internet]. 2017;10(5):582–93. ][77. Mori H, Torii S, Kutyna M, Sakamoto A, Finn A V, Virmani R. Coronary Artery Calcification and its Progression: What Does it Really Mean? JACC Cardiovasc Imaging [Internet]. 2018;11(1):127–42. ][88. Sage AP, Tintut Y, Demer LL. Regulatory mechanisms in vascular calcification. Nat Rev Cardiol [Internet]. 2010 Sep;7(9):528–36. ].

Implications of coronary calcification

The development and coalescence of microcalcifications has been linked to plaque erosion, plaque rupture, plaque destabilisation and luminal obstruction with thrombus formation and has been detected in acute coronary syndromes, both non-ST elevation and ST-elevation myocardial infarctions [99. Jinnouchi H, Sato Y, Sakamoto A, Cornelissen A, Mori M, Kawakami R, et al. Calcium deposition within coronary atherosclerotic lesion: Implications for plaque stability. Atherosclerosis [Internet]. 2020;306:85–95. ]. This is a relatively novel pathophysiological concept, differing from the traditional belief that the finding of a positively remodelled artery with fibrocalcific plaques is a marker of stability, rather than a risk factor for acute events. It is, however, more likely that coronary calcification may be a marker of the extent of coronary disease. It appears that spotty calcifications are associated with unstable plaques and acute coronary syndromes, but not all acute coronary syndromes appear at the site of extensive calcification. Further research is warranted [1010. Nakahara T, Narula J, Strauss H. Calcification and inflammation in atherosclerosis: which is the chicken, and which is the egg? A. Am J Coll Cardiol. 2016;67:79–80. ].

Coronary computerised tomography angiography (CCTA) provides an essential non-invasive technique for the evaluation of coronary anatomy and the quantification of coronary calcification; and in the latest ESC Guidelines for Chronic Coronary Syndrome, coronary CTA is recommended as the initial test for diagnosing CAD in symptomatic patients in whom obstructive CAD cannot be excluded by clinical assessment alone (Class I) [1111. Knuuti J, Wijns W, Saraste A, Capodanno D, Barbato E, Funck-Brentano C, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J [Internet]. 2020;41(3):407–77. ].

The Multi-Ethnic Study of Atherosclerosis (MESA) study showed that the coronary artery calcium score (calculated by the Agatston method) was an independent predictor of coronary events in both symptomatic and asymptomatic patients [1212. Budoff MJ, Young R, Lopez VA, Kronmal RA, Nasir K, Blumenthal RS, et al. Progression of coronary calcium and incident coronary heart disease events: MESA (Multi-Ethnic Study of Atherosclerosis). J Am Coll Cardiol [Internet]. 2013 Mar 26;61(12):1231–9. ][1313. Budoff MJ, Young R, Burke G, Jeffrey Carr J, Detrano RC, Folsom AR, et al. Ten-year association of coronary artery calcium with atherosclerotic cardiovascular disease (ASCVD) events: the multi-ethnic study of atherosclerosis (MESA). Eur Heart J [Internet]. 2018;39(25):2401–8. ][1414. Faggiano P, Dasseni N, Gaibazzi N, Rossi A, Henein M, Pressman G. Cardiac calcification as a marker of subclinical atherosclerosis and predictor of cardiovascular events: A review of the evidence. Eur J Prev Cardiol [Internet]. 2019;26(11):1191–204. ][1515. Trivedi R, Blaha MJ, Blumenthal RS, Cainzos-Achirica M. The Agatston Coronary Artery Calcium Score in Statin Users: Recent Insights from the CAC Consortium and Pathways Forward. American College of Cardiology. 2021. ].

From the perspective of the coronary interventionalist, coronary calcification remains one of the most challenging lesion subsets. It is a marker for advanced atherosclerosis and is often found in patients with complex multivessel disease, chronic total occlusion, long lesions, and bifurcations. The SYNTAX score, which estimates the complexity of coronary disease and aids in selecting the method of revascularisation, allocates 2 points per lesion when there is heavy calcification present on fluoroscopy [1616. Head SJ, Farooq V, Serruys PW, Kappetein AP. The SYNTAX score and its clinical implications. Heart [Internet]. 2014 Jan;100(2):169–77. ].

Calcification limits the ability to deliver and adequately deploy coronary stents with the consequent potential for a suboptimal result, thus increasing the risk of complications such as restenosis or stent thrombosis. Calcification also increases the risk of acute procedural complications such as stent loss and coronary perforation [1717. Brilakis E, Best P, Elesber A, Barsness G, Lennon R, Holmes DJ, et al. Incidence, retrieval methods, and outcomes of stent loss during percutaneous coronary intervention: a large single-center experience. Catheter Cardiovasc Interv. 2005;Nov 66(3):333–40. ]. PCI in severely calcified coronaries has been associated with higher mortality rates, higher rate of death and MI and a higher rate of coronary revascularisation. As such, severe calcified coronary disease is an independent predictor of a worse prognosis following PCI [1818. Bourantas C V, Zhang Y-J, Garg S, Iqbal J, Valgimigli M, Windecker S, et al. Prognostic implications of coronary calcification in patients with obstructive coronary artery disease treated by percutaneous coronary intervention: a patient-level pooled analysis of 7 contemporary stent trials. Heart [Internet]. 2014 Aug;100(15):1158–64. ].

Coronary atherectomy is utilised in less than 5% of PCI patients even though it has been shown that the prevalence of moderate to severe coronary calcification in the PCI patient population is 32% [1919. Arora S, Panaich SS, Patel N, Patel NJ, Savani C, Patel S V, et al. Coronary Atherectomy in the United States (from a Nationwide Inpatient Sample). Am J Cardiol [Internet]. 2016 Feb 15;117(4):555–62. ]. A comparison of bailout atherectomy for uncrossable or undilatable lesions versus planned atherectomy for severe calcification demonstrated shortened procedural time, less contrast utilisation, and lower rates of coronary dissections requiring additional stenting when planned atherectomy was used [2020. Allali A, Abdel-Wahab M, Sulimov DS, Jose J, Geist V, Kassner G, et al. Comparison of Bailout and Planned Rotational Atherectomy for Heavily Calcified Coronary Lesions: A Single-Center Experience. J Interv Cardiol [Internet]. 2017 Apr;30(2):124–33. ].

Numerous therapeutic options have been developed with the view to modifying calcific plaques to facilitate stent delivery and expansion. The most effective therapy for many decades has been rotational atherectomy, originally developed in in the 1980’s. Cutting and scoring balloons have been used with varying degrees of success. The expansion of PCI to treat ever more challenging lesions as a result of advancing patient age and improved PCI technology has resulted in considerable research over the last decade into therapeutic options to modify coronary calcium. Orbital atherectomy and intra-coronary lithotripsy are now additional options and the Rotablator^TM rotational atherectomy system has been upgraded.

This chapter will focus on the diagnosis, evaluation and treatment methods for the safe, effective and efficient PCI of calcific coronary lesions, and will end with an algorithmic approach to coronary calcium management.

Diagnosis of coronary calcification

The assessment of coronary calcification is essential, in order to appropriately manage calcified coronary arteries. Tools available for the assessment of calcification include non-invasive CTA, fluoroscopy at the time of angiography, and intravascular imaging using IVUS or OCT.

Coronary Computerised Tomography Angiography (CCTA)

CCTA is a critical non-invasive diagnostic tool for identifying and classifying coronary calcification. It is identified by any area of hyper-attenuation, defined as a minimum of 1mm² with >130 Hounsfield units, or by having ≥3 adjacent pixels using the Agatston method. The sum of all identified calcium lesions constitutes the calcium score that is used for the predictions of cardiovascular risk for development of future clinical events [2121. Busse A, Cantré D, Beller E, Streckenbach F, Öner A, Ince H, et al. Cardiac CT: why, when, and how : Update 2019. Radiologe [Internet]. 2019 Dec;59(Suppl 1):1–9. ]. Ultrafast CT is more sensitive than fluoroscopy, detecting coronary calcium in 90% versus 52% of cases [2222. Agatston AS, Janowitz WR, Hildner FJ, Zusmer NR, Viamonte M, Detrano R. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol [Internet]. 1990 Mar 15;15(4):827–32. ][2323. Neves PO, Andrade J, Monção H. Coronary artery calcium score: current status. Radiol Bras [Internet]. 50(3):182–9. ]. CCTA is able to characterise coronary calcium plaques, specifically the identification of spotty calcification, which in addition to low CT attenuation, positive remodelling, and the napkin-ring sign, is a marker of vulnerable plaques. Despite this, there are no clearly established criteria by which CCTA can predetermine how PCI should be performed. The calcification remodelling index is a ratio of lumen area of the most severely calcified site to the lumen area of the proximal reference. It has been proposed to evaluate when rotational atherectomy (RA) might be required based on CT criteria. In a retrospective analysis, the calcification remodelling index was significantly correlated with the incidence of using rotational atherectomy (RA) to aid PCI, with an index ≤ 0.84 independently predicting the need for rotational atherectomy prior to stent implantation [2424. Yu M, Li Y, Li W, Lu Z, Wei M, Zhang J. Calcification Remodeling Index Characterized by Cardiac CT as a Novel Parameter to Predict the Use of Rotational Atherectomy for Coronary Intervention of Lesions with Moderate to Severe Calcification. Korean J Radiol [Internet]. 18(5):753–62 ]. This score requires further validation before it becomes clinically useful. Other parameters such as regional Agatston score, calcium volume, and involved calcium arc quadrant were also found to be associated with RA use [2424. Yu M, Li Y, Li W, Lu Z, Wei M, Zhang J. Calcification Remodeling Index Characterized by Cardiac CT as a Novel Parameter to Predict the Use of Rotational Atherectomy for Coronary Intervention of Lesions with Moderate to Severe Calcification. Korean J Radiol [Internet]. 18(5):753–62 ]. An awareness of the need for potential plaque modification should be borne in mind in patients with a high calcium score on CCTA. Coronary calcium deposits are illustrated in ( Figure 1).

Fluoroscopy

In patients who have not undergone CCTA prior to angiography, fluoroscopy may be the first opportunity to diagnose coronary calcification. ( Figure 2A, Figure 2B). Calcification is regarded as moderate when there is radiopacity observed only during the cardiac cycle before contrast is injected, whilst severe calcification is radiopacity seen without cardiac motion, visible as a double track on both sides of the arterial lumen. Angiography however, under-estimates the degree of calcification and is unable to estimate the depth within the plaque. Intravascular imaging (IVUS and OCT) have demonstrated far superior accuracy, and in the presence of angiographic calcification, there should be a low threshold to perform intravascular imaging (see below) [2525. Wang X, Matsumura M, Mintz GS, Lee T, Zhang W, Cao Y, et al. In Vivo Calcium Detection by Comparing Optical Coherence Tomography, Intravascular Ultrasound, and Angiography. JACC Cardiovasc Imaging [Internet]. 2017;10(8):869–79. ].

Occasionally severe calcification can resemble and be mistaken for thrombus when severe calcific nodules prevent contrast penetration and appear as filling defects in the lumen. ( Figure 3).

Intra-vascular Ultrasound (IVUS)

Ultrasound has a resolution of 150–200μm but does not penetrate calcium. The leading edge of calcification can be visualised as a bright hyperechoic deposit but behind the calcium is a blank acoustic shadow and further details of the vessel wall are invisible ( Figure 4). Severe calcification can result in reverberations behind the leading edge of the calcium. Calcium is quantified with IVUS by the arc of uninterrupted calcium (measured in degrees) as well as its length, and it is classified as superficial (close the lumen) or deep (behind the lumen in the deep media or adventitia) where it has little impact on the lumen. The most relevant calcium is superficial calcium in an arc of more than 180° [2525. Wang X, Matsumura M, Mintz GS, Lee T, Zhang W, Cao Y, et al. In Vivo Calcium Detection by Comparing Optical Coherence Tomography, Intravascular Ultrasound, and Angiography. JACC Cardiovasc Imaging [Internet]. 2017;10(8):869–79. ][2626. Mintz GS, Popma JJ, Pichard AD, Kent KM, Satler LF, Chuang YC, et al. Patterns of calcification in coronary artery disease. A statistical analysis of intravascular ultrasound and coronary angiography in 1155 lesions. Circulation [Internet]. 1995 Apr 1;91(7):1959–65. ]. The greater the arc and length of calcium, the greater the likelihood of stent under-expansion.

VH-IVUS is an algorithm for virtual tissue histology using radiofrequency analysis of reflected ultrasound signals. VH-IVUS can better detect calcification which is usually displayed in white on the screen [2727. König A, Klauss V. Virtual histology. Heart [Internet]. 2007 Aug;93(8):977–82. ].

Limitations of IVUS include inability of the catheter to cross highly calcified lesions. This usually implies significant calcification, and calcification modifying tools should be selected accordingly. IVUS is also unable to detect microcalcifications or the full thickness of calcium (IVUS cannot measure calcium depth).

Optical Coherence Tomography (OCT)

OCT has a resolution of 10–20μm. It measures light backscatter and calcium is seen as a low signal area with well-delineated sharp borders ( Figure 5). Because, unlike ultrasound, light penetrates calcium, OCT can assess calcium depth, area, and volume in addition to calcium arc and length. It can also detect microcalcifications [2828. Mehanna E, Bezerra HG, Prabhu D, Brandt E, Chamié D, Yamamoto H, et al. Volumetric characterization of human coronary calcification by frequency-domain optical coherence tomography. Circ J [Internet]. 2013;77(9):2334–40. , 2929. Yabushita H, Bouma BE, Houser SL, Aretz HT, Jang I-K, Schlendorf KH, et al. Characterization of human atherosclerosis by optical coherence tomography. Circulation [Internet]. 2002 Sep 24;106(13):1640–5. ].

Classification of degree of calcification

In order to effectively grade calcium as mild, moderate or severe, the following measurements need to be acquired: the calcium arc; the length of the calcified segment; and the thickness of the calcium.

With both IVUS and OCT, characteristics of mild to moderate calcification include an arc of calcium < 270⁰ and length of the calcified lesion <5mm. Characteristics of severe calcification include an arc of calcium > 270⁰ and length of the calcified lesion >5mm. Due to the ability of OCT to penetrate through calcified plaque, the thickness of calcium can be measured, and calcium thickness of ≥0.5mm is considered a marker of severe calcification. In the event that the IVUS or OCT catheter cannot cross the lesion, it can be assumed that calcification is severe. Scoring systems for coronary calcification have been proposed. One such score, using OCT or IVUS, is presented ( Figure 6). Severe calcification requires calcium modification as the first step in a PCI procedure. In the presence of moderate calcification, operators should have a low threshold for use of calcium-modifying technologies.

Tools for management of coronary calcification during PCI

General Considerations

The arterial access site is dictated by the following key principles: guide size; adjunctive tools to be used (RA, OA, IVL etc); and operator experience. Operators should familiarize themselves with supplementary techniques such as support wiring, buddy wiring, guide extensions, and side branch or distal vessel balloon anchoring when managing calcified lesions. It is also essential to understand the key metrics of the devices available for managing calcified lesions, specifically the dimensions of the device and appropriate corresponding guide size, compatible coronary wires, and balloon crossing profiles as well as their nominal and burst pressures [3030. Sorini Dini C, Nardi G, Ristalli F, Mattesini A, Hamiti B, Di Mario C. Contemporary Approach to Heavily Calcified Coronary Lesions. Interv Cardiol (London, England) [Internet]. 2019 Nov;14(3):154–63. ].

Specialty Balloons

It is mostly not possible, and ill advised, to perform direct stenting in severely calcified coronary arteries. Usually balloon dilatation or plaque modification is required to allow successful stent implantation. Speciality balloons can be divided into two main categories: 1) balloons capable of tolerating high inflation pressures and 2) balloons that have wires or blades designed to cut or score into coronary calcium.

High- and Very High-pressure Non-Compliant Balloons

Non-compliant balloons (NC) are designed to inflate to high pressures with only small incremental diameter changes, allowing for the application of high pressure to a focal segment of the coronary lesion. This avoids a dog-bone deformity and reduces the risk of dissection and perforations when inflating to higher pressures [3131. Raja Y, Routledge HC, Doshi SN. A noncompliant, high pressure balloon to manage undilatable coronary lesions. Catheter Cardiovasc Interv [Internet]. 2010 Jun 1;75(7):1067–73. ]. NC balloons should be considered as the first choice of treatment for mild to moderate calcification (calcium arc <90º).

Within this category of NC balloons, the OPN NC balloon (SIS Medical) is designed to allow super high pressure within the balloon with minimal diameter change. This is achieved by the unique twin-layer, balloon-in-balloon technology which allows for increased tensile strength while ensuring uniform expansion. They have a crossing profile of 0.71 and range in sizes 1.5 to 4.5 mm (in 0.5 mm increments) and are 10, 15 or 20 mm in length. Nominal pressure is approximately 10Atm and even though the rated burst pressure (RBP) is approximately 35Atm, the balloon has been tested up to 55Atm (maximum inflation allowed by the special indeflator provided) without rupture. The main indications for use include in-stent restenosis, calcified lesions, and resistant (non-dilatable) lesions [3232. Secco GG, Ghione M, Mattesini A, Dall’Ara G, Ghilencea L, Kilickesmez K, et al. Very high-pressure dilatation for undilatable coronary lesions: indications and results with a new dedicated balloon. EuroIntervention [Internet]. 2016 Jun 20;12(3):359–65. ][3333. Secco GG, Buettner A, Parisi R, Pistis G, Vercellino M, Audo A, et al. Clinical Experience with Very High-Pressure Dilatation for Resistant Coronary Lesions. Cardiovasc Revasc Med [Internet]. 2019 Dec;20(12):1083–7. ].

The ISAR-CALC randomised trial compared super high-pressure OPN balloon to scoring balloons (see below) to prepare severely calcified coronary lesions. It showed comparable stent expansion (evaluated by OCT) and a trend towards improved angiographic performance of the ultra-high pressure balloon [3434. Rheude T, Rai H, Richardt G, Allali A, Abdel-Wahab M, Sulimov DS, et al. Super high-pressure balloon versus scoring balloon to prepare severely calcified coronary lesions: the ISAR-CALC randomised trial. EuroIntervention. 2021;17:481–8. ]. In clinical experience, there is a reported success rate of >90% for undilatable lesions compared to conventional NC balloons, with less than 1% rate of coronary rupture [3333. Secco GG, Buettner A, Parisi R, Pistis G, Vercellino M, Audo A, et al. Clinical Experience with Very High-Pressure Dilatation for Resistant Coronary Lesions. Cardiovasc Revasc Med [Internet]. 2019 Dec;20(12):1083–7. ].

Cutting and Scoring Balloons

Cutting balloons have three or four metal microblades on the surface of the balloon, designed to make radial incisions in the media. They therefore reduce elastic recoil, minimise neointimal proliferation and prevent slippage of the balloon during inflation. Initially clinical experience proved to be superior to traditional balloon angioplasty, especially in terms of achieving greater luminal enlargement. Subsequent randomised data comparing conventional balloon to cutting balloon angioplasty for de novo undilatable lesions showed similar procedural success rates and 6-month restenosis rates, at the expense of greater perforation rates in the cutting balloon group. This data, and their relatively large crossing profiles (1.04 to 1.17mm) has limited their use in current clinical practice. The ESC and AHA guidelines have restricted their use to resistant lesions.

In an IVUS-based study, cutting balloon achieved larger luminal gain than regular balloons in calcified lesions [3535. Okura H, Hayase M, Shimodozono S, Kobayashi T, Sano K, Matsushita T, et al. Mechanisms of acute lumen gain following cutting balloon angioplasty in calcified and noncalcified lesions: an intravascular ultrasound study. Catheter Cardiovasc Interv [Internet]. 2002 Dec;57(4):429–36. ].

The Flextome™ Cutting Balloon (Boston Scientific Corp, Natick, MA) was first introduced in 1991, and has since been upgraded to the newer, lower profile (0.914mm) Wolverine™ balloon, designed for improved flexibility and deliverability.

Scoring Balloons

Scoring balloons are semi-compliant balloons encircled by nitinol spiral wires. They serve as anchors when dilating calcified or fibrotic lesions, decreasing balloon slippage, and allowing for focal, concentrated pressure (or force) during inflation. Their indications for use are similar to cutting balloons, but generally are more deliverable due to lower crossing profiles (0.81-1.27mm) and greater flexibility. They can also be fully expanded at relatively lower inflation pressure therefore lowering the risk of perforation and severe dissections [3636. Jujo K, Saito K, Ishida I, Kim A, Suzuki Y, Furuki Y, et al. Intimal disruption affects drug-eluting cobalt-chromium stent expansion: A randomized trial comparing scoring and conventional balloon predilation. Int J Cardiol [Internet]. 2016 Oct 15;221:23–31. ].

Examples of scoring balloons include:

1. AngioSculpt Scoring Balloon (Spectranetics, Colorado Springs, CO) and the drug-coated version, AngioSculpt X (Spectranetics, Colorado Springs, CO) are semi-compliant balloons with three spiral rectangular Nitinol scoring elements with a crossing profile of 0.91mm.
2. NSE Alpha (B Braun) has three triangular flexible nylon elements on the balloon surface that are attached only at the proximal and distal edges (crossing profile 1.27mm).
3. Scoreflex (Orbus Neich) is a semi-compliant balloon with two fixed Nitinol wires on opposite sides of the balloon surface with a crossing profile of 0.81mm.

Both cutting and scoring balloons have been demonstrated to be effective and safe in the treatment of complex coronary lesions [3737. Fonseca A, Costa J de R, Abizaid A, Feres F, Abizaid AS, Costa R, et al. Intravascular ultrasound assessment of the novel AngioSculpt scoring balloon catheter for the treatment of complex coronary lesions. J Invasive Cardiol [Internet]. 2008 Jan;20(1):21–7. ][3838. de Ribamar Costa J, Mintz GS, Carlier SG, Mehran R, Teirstein P, Sano K, et al. Nonrandomized comparison of coronary stenting under intravascular ultrasound guidance of direct stenting without predilation versus conventional predilation with a semi-compliant balloon versus predilation with a new scoring balloon. Am J Cardiol [Internet]. 2007 Sep 1;100(5):812–7. ][3939. Redfors B, Maehara A, Witzenbichler B, Weisz G, Stuckey TD, Henry TD, et al. Outcomes After Successful Percutaneous Coronary Intervention of Calcified Lesions Using Rotational Atherectomy, Cutting-Balloon Angioplasty, or Balloon-Only Angioplasty Before Drug-Eluting Stent Implantation. J Invasive Cardiol [Internet]. 2017 Nov;29(11):378–86. ][4040. Singh A, Kirtane A, Moses J. AngioSculptSB scoring balloon catheter: an atherotomy device for coronary and peripheral interventions. Interv Cardiol. 2010;(2):469–78. ].

Compared with standard balloon predilatation, high-speed rotational atherectomy (RA) is associated with higher initial procedural success [4141. Abdel-Wahab M, Richardt G, Joachim Büttner H, Toelg R, Geist V, Meinertz T, et al. High-speed rotational atherectomy before paclitaxel-eluting stent implantation in complex calcified coronary lesions: The randomized ROTAXUS (Rotational Atherectomy Prior to Taxus Stent Treatment for Complex Native Coronary Artery Disease) trial. JACC Cardiovasc Interv [Internet]. 2013;6(1):10–9. ]. Whether specialised balloons (scoring or cutting balloons) could achieve similar procedural success compared with RA was investigated. 200 patients were randomised to lesion preparation with either RA or specialised balloons, followed by stenting. Procedural success was significantly higher with RA preparation compared to specialised balloons (98% vs 81%) and fluoroscopy time was significantly higher with specialised balloons. 9-month late loss, TLR, stent thrombosis and TVF were not significantly different.

Therefore, while specialised balloons may have a role in mild to moderate calcified coronary lesions, they are less effective than atherectomy or lithotripsy (see later) and should be used as adjuncts to these strategies when dealing with moderate to severe calcified lesions.

Rotational Atherectomy

Percutaneous transluminal rotational atherectomy (RA) was developed in the pre-stent era, as an interventional tool designed to achieve improved angioplasty results for difficult to dilate, calcified, diffusely diseased atherosclerotic lesions. David Auth first proposed a rotational debulking device in the 1980’s, eventually resulting in Fourier et al performing the first in human RA in 1988 [4242. Hansen DD, Auth DC, Vracko R, Ritchie JL. Rotational atherectomy in atherosclerotic rabbit iliac arteries. Am Heart J [Internet]. 1988;115(1):160–5. ][4343. Hansen D, Auth D, Vracko R, Ritchie J. Mechanical thrombectomy: a comparison of two rotational devices and balloon angioplasty in subacute canine femoral thrombosis. Am Hear J. 1987;114(5):1223–31. ][4444. Cavusoglu E, Kini AS, Marmur JD, Sharma SK. Current status of rotational atherectomy. Catheter Cardiovasc Interv. 2004;62(July 2003):485–98. ]. With the advent of stenting, and the knowledge that residual plaque burden at the time of stenting is directly proportional to the degree of neointimal proliferation, it was hypothesised that maximum mechanical debulking would reduce the risk of stent restenosis [4545. Prati F, Di Mario C, Moussa I, Reimers B, Mallus M, Parma A, et al. In-stent neointimal proliferation correlates with the amount of residual plaque burden outside the stent: an intravascular ultrasound study. Circulation. 1999;99:1011–4. ]. RA, it was thought, would be beneficial by decreasing the underlying plaque burden, increasing the acute procedural minimal luminal diameter (MLD), and would decrease the risk of abrupt closure by preserving the original arterial size and limit the degree of barotrauma to the vessel [4646. Hinohara T, Rowe MH, Robertson GC, Selmon MR, Braden L, Leggett JH, et al. Effect of lesion characteristics on outcome of directional coronary atherectomy. J Am Coll Cardiol. 1991;17(5):1112–20. ]. Despite these premises, clinical trials have failed to show either an improved mortality or rate of target lesion revascularisation (TLR) with mechanical debulking over conventional PCI, limiting the initial widespread use of this technique [4747. King SB, Yeh W, Holubkov R, Baim DS, Sopko G, Desvigne-Nickens P, et al. Balloon Angioplasty Versus New Device Intervention: Clinical Outcomes. J Am Coll Cardiol. 1998;31(3):558–66. ][4848. Bittl J a., Chew DP, Topol EJ, Kong DF, Califf RM. Meta-analysis of randomized trials of percutaneous transluminal coronary angioplasty versus atherectomy, cutting balloon atherotomy, or laser angioplasty. J Am Coll Cardiol. 2004;43(6):936–42. ].

The advent of drug-eluting stents (DES) resulted in a reduction in in-stent restenosis (ISR) rates to below 10% [4949. Stone G, Ellis S, Cox D, Hermiller J, O’Shaughnessy C, Mann J, et al. A polymer-based, paclitaxel-eluting stent in patients with coronary artery disease. New Engl J. 2004;15(350(3)):221–31. ][5050. Machado C, Raposo L, Dores H, Leal S, Campante Teles R, de Araújo Gonçalves P, et al. Second-generation versus first-generation drug-eluting stents for the treatment of patients with acute coronary syndromes and obstructive coronary artery disease. Coron Artery Dis [Internet]. 2014 May [cited 2014 Nov 1];25(3):208–14. ]. As a result more complex lesions began to be treated by PCI and this brought with it procedural challenges in dealing with difficult coronary anatomy. In particular, calcified and tortuous vessels present unique problems for the delivery and deployment of DES. In addition, calcified lesions are potentially prone to reduce long-term efficacy and safety of DES as a result of underexpansion or polymer disruption, likely translating to a higher restenosis rates and the potential risk of stent thrombosis [5151. Lee W-S, Charng M-J. Rotational atherectomy in the era of drug-eluting stents. J Chin Med Assoc [Internet]. 2013 Apr [cited 2014 Oct 20];76(4):180–1. ][5252. Kuriyama N, Kobayashi Y, Yamaguchi M, Shibata Y. Usefulness of rotational atherectomy in preventing polymer damage of everolimus-eluting stent in calcified coronary artery. JACC Cardiovasc Interv [Internet]. 2011 May [cited 2014 Nov 3];4(5):588–9. ]. These concerns, along with a higher incidence of complex procedures and calcified lesions in a progressively ageing patient population have given new life to RA, now playing a role complementary to PTCA and stenting, rather than as a stand-alone tool [5353. Tran T, Brown M, Lasala J. An evidence-based approach to the use of rotational and directional coronary atherectomy in the era of drug-eluting stents: When does it make sense? Catheter Cardiovasc Interv. 2008;72(May):650–62. ]. RA has shown excellent results in enhancing procedural success, but this has not translated into a consistent long-term benefit in terms of restenosis and major adverse cardiac events (MACE) [5454. Chiang M-H, Lee W-L, Tsao C-R, Chang W-C, Su C-S, Liu T-J, et al. The use and clinical outcomes of rotablation in challenging cases in the drug-eluting stent era. J Chin Med Assoc [Internet]. 2013 Feb [cited 2014 Oct 20];76(2):71–7. ]. As a result, RA was officially recommended for the preparation of heavily calcified or severely fibrotic lesions which cannot be crossed by a balloon or be adequately dilated before planned stenting (Class I recommendation, level of evidence C). The 2014 version of the European Society of Cardiology (ESC)/European Association of Cardio-Thoracic Surgery (EACTS) Guideline for Myocardial Revascularisation recommends RA as a reasonable procedure for fibrotic or heavily calcified lesions that might not be crossed by a balloon catheter or adequately dilated before stent implantation (Class IIa, level of evidence C) [5555. Windecker S, Kolh P, Alfonso F, Collet J-P, Cremer J, Falk V, et al. 2014 ESC/EACTS Guidelines on myocardial revascularization: The Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) Developed with the special contribution. Eur J Cardiothorac Surg [Internet]. 2014 Aug 29 [cited 2014 Sep 2];46(August):517–92. ]. The 2018 Guideline mentions that rotational atherectomy may be required in selected lesions, particularly those with heavy calcification, in order to adequately dilate lesions prior to stent implantation [5656. Neumann F-J, Sousa-Uva M, Ahlsson A, Alfonso F, Banning, Adrian P Benedetto U, Byrne RA, et al. 2018 ESC/EACTS Guidelines on myocardial revascularization. Eur Heart J. 2018;40(2):87–165. ].

Principles of rotational atherectomy

RA is performed by advancing a high-speed rotating metallic burr through a calcified plaque. The burr ( Figure 7) is elliptical shaped and is coated on its front end by diamond particles, acting as a rotatory abrasive surface. The principles of differential cutting and orthogonal displacement of friction allow high-speed mechanical ablation of calcified atheroma while sparing normal adjacent tissue [4444. Cavusoglu E, Kini AS, Marmur JD, Sharma SK. Current status of rotational atherectomy. Catheter Cardiovasc Interv. 2004;62(July 2003):485–98. ].

Differential cutting ( Figure 8) refers to the ability to ablate one material while sparing another material with an alternate substrate composition. By this mechanism the rotating burr preferentially ablates inelastic atherosclerotic plaque while not affecting the adjacent normal, elastic compliant vessel wall. This is contrary to the effect of standard balloon dilatation, where there is plaque disruption at the weakest point of the plaque, resulting in intentional intimal tears and dissections at the calcific and non-calcific interface. Plaque dissections occur less frequently with RA (26%), as compared to balloon angioplasty where it occurs in 66%-73% of cases [5757. Kovach J, Mintz G, Pichard A, Kent K, Popma J, Satler L, et al. Sequential intravascular ultrasound characterization of the mechanisms of rotational atherectomy and adjunct balloon angioplasty. J Am Coll Cardiol. 1993;22(4):1024–32. ][5858. Honye J, Mahon D, Jain A, White C, Ramee S, Wallis J, et al. Morphological effects of coronary balloon angioplasty in vivo assessed by intravascular ultrasound imaging. Circulation. 1992;85(3):1012–25. ][5959. Potkin BN, Keren G, Mintz GS, Douek PC, Pichard a D, Satler LF, et al. Arterial responses to balloon coronary angioplasty: an intravascular ultrasound study. J Am Coll Cardiol. 1992;20:942–51. ][6060. Eltchaninoff H, Cribier A, Koning R, Chan C, Sicard V, Tan A, et al. Angioscopic Evaluation of Rotational Atherectomy Followed by Additional Balloon Angioplasty Versus Balloon Angioplasty Alone in Coronary Artery Disease : A Prospective , Randomized Study. J Am Coll Cardiol. 1997;30(4):888–93. ].

Burr rotation causes orthogonal displacement of friction. At rotational speeds of greater than 60000 revolutions per minute (rpm), the burr-to-vessel surface friction is virtually eliminated, thereby reducing surface drag and allowing unimpeded forward-and-back movement of the burr through the diseased vessel.

The abraded plaque is reduced to micro-particles which are 5-10µm in diameter: ( Figure 9) a combination of fine granular calcification composed of collagen and necrotic plaque core, and larger calcific nodular deposits. These particles embolise distally but are small enough to pass through the coronary microcirculation and are finally phagocytosed by the reticuloendothelial system in the liver, spleen and lungs. The avoidance of formation of more problematic larger particles is dependent on proper procedural technique described below.

Components of the Rotablator™ SYSTEM

The Rotablator^TM rotational atherectomy system is the most widely used atherectomy tool for the pre-treatment of difficult to dilate, calcified atherosclerotic lesions (Boston Scientific Corporation, Natick, Boston, MA, USA). The Rotablator^TM components had been unchanged for many decades, but in 2018, an upgraded system called the Rotapro^TM was released. The Rotapro^TM system has an upgraded console and advancer. The other components listed below remain unchanged. There remain many functioning Rotablator^TM systems worldwide and therefore both variants are described below.

The individual components include:*

RotaWire^TM guide wires ( Figure 10)

Burrs ( Figure 1, Figure 11)

Advancer:

• RotaLink^TM Advancer (the burrs and advancer are available separately or pre-connected: RotaLink^TM Plus) ( Figure 12)
• Rotapro^TM Advancer ( Figure 13)

Console:

• Rotablator^TM Console and Foot Pedal ( Figure 14 , Figure 15)
• Rotapro^TM Console ( Figure 16)

Rotaglide™ Lubricant ( Figure 17)

Rotablator^TM guide wires

The current Rotablator^TM system is compatible with two guide wires – the RotaWire Floppy guidewire and Extra Support guidewire. The floppy wire has a long, tapered shaft, allowing greater flexibility and making it easier to cannulate the culprit-lesion vessel. The extra support wire has a shorter tapered shaft and thereby provides more support to maximise vessel straightening and device delivery. Both wires are made from a specially designed stainless steel (dimensions: 0.009 inch diameter, 300cm length), and have a radiopaque platinum distal tip (dimensions: 0.014 inch diameter, 22 mm length). The radiopaque portion is visible under fluoroscopy. These guide wires also help keep the abrasive burr tip coaxial with the vessel lumen. Conventional guide wires are not compatible with the Rotablator^TM system because they have a larger diameter and they have coatings which would be stripped off during rotation, and therefore cannot be used for RA. The WireClip™ torquer is the only torquer compatible with RotaWires ( Figure 18). Newer more contemporary wires are under development and will be available in the near future.

Burrs

The most critical aspect of RA is the design of the burr ( Figure 7, Figure 19 ). The elliptical shaped head of the burr is moulded from nickel-plated brass (diameters ranging from 1.25 to 2.50 mm). The distal end of the burr head is coated with 2000 to 3000 microscopic (20 to 30 microns) diamond crystals, with approximately 5 microns of each the crystal protruding from the nickel coating. The proximal end of the burr is smooth. The burr is attached to a nickel-plated brass drive shaft (135cm long). This drive shaft ( Figure 7) is covered in a Teflon casing (4.3F protective sheath) ( Figure 7), preventing the rotating components from injuring the artery. It also allows for the continuous infusion of a medicated saline solution along the drive shaft throughout the procedure. Since the drive shaft is rotating at high speeds, the saline solution is needed to cool and lubricate the rotating components.

The Rotablator^TM system is an over-the-wire system, with the proximal end of the burr allowing entry for the guide wire. The guide wire passes the full length of the drive shaft, through the advancer, and exits at the back of advancer ( Figure 20) to allow for operator wire control.

The burr can be disconnected and exchanged for a different size burr if required ( Figure 21). When larger burr sizes are used, the guiding catheter may need to be upsized.

ROTABLATOR™ advancer, console and foot pedal

The Rotablator RotaLink™ advancer ( Figure 12) has the following key components: advancer body, burr control knob, saline infusion port, fibre optic tachometer cable connection, and the advancer hose with the compressed gas connector.

The front end of the advancer body is attached to the driveshaft of the burr. The back end of the advancer has the opening for the guide wire to exit. The burr control knob lies in the centre of the advancer. Unscrewing the knob allows one to slide the knob forward to advance the burr. Retracting the knob returns the burr to its starting position, allowing for the forward-and-back motion of the burr through the lesion.

From the side of the advancer, the advancer hose connects to the cylinder of compressed gas ( Figure 22). A motor compresses air and transports high pressure nitrogen to the turbine of the advancer body, converting the high-pressure air into rotational energy, which in turn rotates the drive shaft at high speeds. The rotating drive shaft allows the burr to rotate at speeds of up to 200 000 rpm. The fibre optic tachometer cable measures the rpm of the rotating burr. It attaches to the console ( Figure 13), which gives a visual readout of rpm, and allows the operator to control the speed and air inflow. The Rotablator DynaGlide™ Foot Pedal ( Figure 14) attaches to the console and activates the burr by initiating the flow of air through the system. It also facilitates burr advancement or removal by switching the system from rotablation to DynaGlide mode. A DynaGlide switch is located next to the main pedal. Upon DynaGlide activation, a light indicator appears on the console, and the burr can be retrieved at a controlled speed rotation of 60,000-90,000 rpm. During burring, an automatic wire break prevents the wire from spinning. Before retrieving the burr, in order to free the RotaWire™, the break defeat button next to the docking port needs to be pressed.

A saline infusion port on the side of the advancer body allows entrance into the drive shaft sheath for the continuous infusion of saline (usually mixed with verapamil or nitroglycerine) to reduce heat, friction, and spasm. Rotaglide™ lubricant is a specially designed fluid that increases lubricity, facilitating the delivery of the system. It is also designed to further reduce heat and friction during burr advancement, as well as reduce the overall force required to advance the burr. Many cathlabs no longer use the Rotaglide™ lubricant since saline mixed with the above medications is equally effective.

Rotapro™ advancer and console

The Rotapro™ advancer ( Figure 13) incorporates the functions of the foot pedal into the advancer. The DynaGlide switch is at the back of the advancer with an adjacent DynaGlide indicator light. There is also a “DynaGlide momentary-on” button for activation of DynaGlide. This button needs to be continuously depressed to use DynaGlide mode. The start/stop switch is a button at the top of the advancer knob. The connections to the console (electrical, gas line and fibre optic) are now incorporated into a single cable. The remainder of the advancer features are the same as the Rotablator™ advancer. The Rotapro™ advancer can be selected pre-attached to a chosen burr, or separately.

The Rotapro™ console ( Figure 16) is compact and can be mounted on pole. A smaller gas bottle can be mounted within the console assembly. There are ports for electrical, gas line and fibre optic connections and a rpm adjustment knob. A digital display indicates the rotational speed, the event time for the last start/stop cycle and the total procedure time. There is also a timer reset button.

The console has warning indicators for the following conditions ( Figure 23):

• Deceleration more than 5000 rpm (yellow triangle outline)
• Deceleration more than 10000 rpm (solid yellow triangle)
• Deceleration more than 15000 rpm (red “stall” indication)
• Inadequate pressure to the console (yellow “check pressure” indication)
• DynaGlide active (green “DynaGlide” indication)

At the back of the console are the power connector, on/off switch and gas line connector.

The Rotablator™ procedure

Indications and strategies

It is well established that the degree of late restenosis is directly proportional to acute gain of luminal diameter achieved from PTCA [6161. Kuntz R, Gibson M, Nobuyoshi M, Baim D. Generalized Model of Restenosis After Conventional Balloon Angioplasty, Stenting and Directional Atherectomy. J Am Coll Cardiol. 1993;21(1):15–25. ]. RA was originally developed in the pre-stent era as an attempt to improve conventional balloon angioplasty (POBA), especially in lesions that were recognised as being poor candidates for POBA. These included patients with diffuse disease, heavily calcified lesions, ostial disease, and restenosis after previous PTCA [6262. Teirstein PS, Warth FDC, Haq N, Jenkins NS, Linda RN, Aubanel-reidel P, et al. High Speed Rotational Coronary Atherectomy for Patients With Diffuse Coronary Artery Disease. 1991;. ][6363. Reifart N, Vandormael M, Krajcar M, Gohring S, Preusler W, Schwarz F, et al. Randomized Comparison of Angioplasty of Complex Coronary Lesions at a Single Center : Excimer Laser, Rotational Atherectomy, and Balloon Angioplasty Comparison (ERBAC) Study. Circulation [Internet]. 1997 Jul 1 [cited 2014 Oct 20];96(1):91–8. ].

Procedural success was improved with RA but there was no significant difference in terms of the long-term clinical or angiographic outcomes between PTCA and RA [6464. Dill T, Dietz U, Hamm CW, Küchler R, Rupprecht HJ, Haude M, et al. A randomized comparison of balloon angioplasty versus rotational atherectomy in complex coronary lesions (COBRA study). Eur Heart J [Internet]. 2000 Nov [cited 2014 Oct 20];21(21):1759–66. ]. Even in small vessels (<3.0mm in diameter), although there was no benefit of RA over PTCA, RA was as safe and as effective as PTCA [6565. Whitlow PL, Bass TA, Kipperman RM, Sharaf BL, Ho KKL, Cutlip DE, et al. Results of the study to determine rotablator and transluminal angioplasty strategy (STRATAS). Am J Cardiol. 2001;87:699–705. ][6666. Mauri L, Reisman M, Buchbinder M, Popma JJ, Sharma SK, Cutlip DE, et al. Comparison of rotational atherectomy with conventional balloon angioplasty in the prevention of restenosis of small coronary arteries: results of the Dilatation vs Ablation Revascularization Trial Targeting Restenosis (DART). Am Heart J [Internet]. 2003 May [cited 2014 Nov 1];145(5):847–54. ].

A number of trials have offered insight into the best methodology for RA. RA performed best when decelerations > 5000rpm drop were cumulatively less than 5 seconds (less peri-procedural CK elevation) [6565. Whitlow PL, Bass TA, Kipperman RM, Sharaf BL, Ho KKL, Cutlip DE, et al. Results of the study to determine rotablator and transluminal angioplasty strategy (STRATAS). Am J Cardiol. 2001;87:699–705. ]. Revolution speeds (140000 to 180000 rpm) and a repetitive pecking motion ( Video 1) of the burr into the proximal portion of the lesion to avoid large decelerations have yielded the most favourable outcomes [6767. Safian RD, Feldman T, Muller DWM, Mason D, Schreiber T, Haik B, et al. Coronary Angioplasty and Rotablator Atherectomy Trial (CARAT): Immediate and late results of a prospective multicenter randomized trial. Catheter Cardiovasc Interv. 2001;53(January):213–20. ]. This motion pattern of the burr allows for frequent intermittent blood flow through the ablated segment, improving wash-out of the debris and potentially reducing heat generation as well as vessel spasm [4444. Cavusoglu E, Kini AS, Marmur JD, Sharma SK. Current status of rotational atherectomy. Catheter Cardiovasc Interv. 2004;62(July 2003):485–98. ]. A rotational speed greater than 60000 rpm is needed to overcome frictional forces and facilitate the passage and retrieval of the burr [6868. Kiesz RS, Rozek MM, Ebersole DG, Mego DM, Chang CW, Chilton RL. Novel approach to rotational atherectomy results in low restenosis rates in long, calcified lesions: Long-term results of the San Antonio Rotablator Study (SARS). Catheter Cardiovasc Interv. 1999;48(December 1998):48–53. ]. On the other hand, very high rotational speeds have been reported to increase distal embolization and procedural myocardial infarction, as a result of excessive heat generation and platelet activation [4444. Cavusoglu E, Kini AS, Marmur JD, Sharma SK. Current status of rotational atherectomy. Catheter Cardiovasc Interv. 2004;62(July 2003):485–98. ].

With more aggressive debulking (a burr: artery ratio >0.7) there was no benefit over PTCA [4949. Stone G, Ellis S, Cox D, Hermiller J, O’Shaughnessy C, Mann J, et al. A polymer-based, paclitaxel-eluting stent in patients with coronary artery disease. New Engl J. 2004;15(350(3)):221–31. ]. Routine lesion modification using small burrs (burr: artery ratio <0.7) achieved similar immediate lumen enlargement and late vessel revascularisation compared to aggressive debulking, but it was also associated with fewer angiographic complications (including coronary dissection, side branch occlusion and the need for bailout stenting). Patients who received larger burr sizes were more likely to experience serious angiographic complications, including dissection, slow or no reflow, and perforation [6767. Safian RD, Feldman T, Muller DWM, Mason D, Schreiber T, Haik B, et al. Coronary Angioplasty and Rotablator Atherectomy Trial (CARAT): Immediate and late results of a prospective multicenter randomized trial. Catheter Cardiovasc Interv. 2001;53(January):213–20. ].

In the stent era, RA was evaluated as a lesion preparation strategy in difficult to dilate lesions prior to stenting – introducing the concept of “Rota-stenting”. Despite a better procedural success rate and larger post-treatment minimal luminal diameter with Rota-stenting, there was no significant difference in MACE, or restenosis [6969. Buchbinder M, Fortuna R, Sharma S, Bass T, Kipperman R, Greenberg J. Debulking prior to stenting improves acute outcomes: early results from the SPORT trial. J Am Coll Cardiol. 2000;. ][7070. Dunn B. Effect of debulking on restenosis (EDRES) Trial. J Saudi Hear Assoc. 1998;10(55). ].

It therefore became clear that RA has a defined clear role as a technique to improve procedural outcome and broaden the number of lesions eligible for PCI rather than a technique to prevent restenosis.

Drug-eluting stents (DES) have largely eliminated the adverse event of post-procedure restenosis. As a result, more complex lesions and vessels are treated in the DES era. DES has a twofold higher failure rate of successful deployment in calcified lesions [7171. Moussa I, Ellis SG, Jones M, Kereiakes DJ, McMartin D, Rutherford B, et al. Impact of coronary culprit lesion calcium in patients undergoing paclitaxel-eluting stent implantation (a TAXUS-IV sub study). Am J Cardiol [Internet]. 2005 Nov 1 [cited 2014 Nov 3];96(9):1242–7. ]. In addition, the placement of DES in tortuous vessels and calcified lesions has been shown to cause major surface damage of the DES polymer and drug [5252. Kuriyama N, Kobayashi Y, Yamaguchi M, Shibata Y. Usefulness of rotational atherectomy in preventing polymer damage of everolimus-eluting stent in calcified coronary artery. JACC Cardiovasc Interv [Internet]. 2011 May [cited 2014 Nov 3];4(5):588–9. ][7272. Wiemer M, Butz T, Schmidt W, Schmitz K-P, Horstkotte D, Langer C. Scanning electron microscopic analysis of different drug eluting stents after failed implantation: from nearly undamaged to major damaged polymers. Catheter Cardiovasc Interv [Internet]. 2010 May 1 [cited 2014 Oct 20];75(6):905–11. ]. Under-deployment of DES within complex lesions is associated with an increased risk of stent thrombosis [7373. Fujii K, Carlier SG, Mintz GS, Yang Y, Moussa I, Weisz G, et al. Stent underexpansion and residual reference segment stenosis are related to stent thrombosis after sirolimus-eluting stent implantation: an intravascular ultrasound study. J Am Coll Cardiol [Internet]. 2005 Apr 5;45(7):995–8. ]. These issues are even more pertinent with the use of bioresorbable scaffolds (BRS) which are more bulky and difficult to deliver and take up more luminal space when under-expanded [7474. Basavarajaiah S, Naganuma T, Latib A, Colombo A. Can bioabsorbable scaffolds be used in calcified lesions? Catheter Cardiovasc Interv. 2014;84:48–52. ]. Theoretically, these limitations can all be successfully overcome by adequate lesion preparation using RA prior to DES/BRS implantation for heavily calcified lesions. RA-DES has been compared to routine stenting in calcified and complex lesions. There was more procedural success in the RA-DES group [4141. Abdel-Wahab M, Richardt G, Joachim Büttner H, Toelg R, Geist V, Meinertz T, et al. High-speed rotational atherectomy before paclitaxel-eluting stent implantation in complex calcified coronary lesions: The randomized ROTAXUS (Rotational Atherectomy Prior to Taxus Stent Treatment for Complex Native Coronary Artery Disease) trial. JACC Cardiovasc Interv [Internet]. 2013;6(1):10–9. ].

The problem with all randomised trials of rotational atherectomy is that the patients who most need RA are not eligible for any alternative treatment option and cannot therefore be randomised. They simply cannot be treated without RA. Contemporary observational data confirm the efficacy and safety of a RA-DES strategy for heavily calcified lesions, with low procedural complication rates and low out-of-hospital MACE [7575. Mezilis N, Dardas P, Ninios V, Tsikaderis D. Rotablation in the drug eluting era: immediate and long-term results from a single center experience. J Interv Cardiol [Internet]. 2010 Jun [cited 2014 Oct 20];23(3):249–53. ][7676. Seca L, Cac R, Silva J, Mota P, Costa M, Marques AL. Rotational atherectomy in the drug-eluting stent era : A recent single-center experience ଝ. 2012;31(1). ][7777. Li Q, Liu J, Lu M-Y, Ma Y-L, Zhao H, Ding R-J, et al. Safety and efficacy of rotational atherectomy followed by drug-eluting stenting for treating patients with heavily calcified coronary lesions. Zhonghua Xin Xue Guan Bing Za Zhi [Internet]. 2013 Jun;41(6):457–61. ].

In summary, in undilatable or heavily calcified lesions, RA procedural success rate ranges from 89% to 98% [6868. Kiesz RS, Rozek MM, Ebersole DG, Mego DM, Chang CW, Chilton RL. Novel approach to rotational atherectomy results in low restenosis rates in long, calcified lesions: Long-term results of the San Antonio Rotablator Study (SARS). Catheter Cardiovasc Interv. 1999;48(December 1998):48–53. ][7171. Moussa I, Ellis SG, Jones M, Kereiakes DJ, McMartin D, Rutherford B, et al. Impact of coronary culprit lesion calcium in patients undergoing paclitaxel-eluting stent implantation (a TAXUS-IV sub study). Am J Cardiol [Internet]. 2005 Nov 1 [cited 2014 Nov 3];96(9):1242–7. ][7878. MacIsaac AI, Bass TA, Buchbinder M, Cowley MJ, Leon MB, Warth DC, et al. High speed rotational atherectomy: outcome in calcified and noncalcified coronary artery lesions. J Am Coll Cardiol [Internet]. 1995 Sep;26(3):731–6. ]. The main role of RA is to improve procedural outcome and broaden the number of lesions eligible for PCI.

Appropriate use of RA

In lesions that are appropriate for PCI, RA is a tool designed to make PCI possible in complex lesions with moderate to severe calcification. Tomey et al have recently proposed an algorithm ( Figure 24) for the appropriate selection of RA which included performing intra-coronary imaging with IVUS or OCT to further classify lesions with angiographically moderate calcification [7979. Tomey MI, Kini AS, Sharma SK. Current Status of Rotational Atherectomy. JACC Cardiovasc Interv [Internet]. 2014;7(4):345–53. ].

Contraindications

Labelled contraindications to RA include occlusions through which a coronary wire will not pass, lesions in the last remaining vessel in patients with compromised left ventricular function, lesions in saphenous vein grafts, angiographic evidence of thrombus, and angiographic evidence of significant dissection at the treatment site.

These labelled contraindications, however, represent scenarios in which RA is sometimes required due to long-standing, extensive disease. Despite these stipulated contraindications, several case reports illustrate the safety and efficacy of RA in exceptional circumstances. These include RA to severely calcified non-dilatable saphenous vein graft lesions, iatrogenic coronary artery dissection, acute myocardial infarction, and calcified unprotected left main lesions in patients deemed ineligible for CABG. However, these scenarios should be tackled only by expert advanced RA operators. (See below in the section on novel off-label uses)

Lesions in last remaining vessels and poor LV function have been successfully treated with meticulous patient preparation and RA technique and haemodynamic support.

Labelled and relative contraindications to rotational atherectomy are listed in Table 1.

Procedure

From the data presented above, different protocols for rotational atherectomy have been suggested in an attempt to obtain the highest acute and at long-term success rate with the lowest risk of procedural complications. The fundamental elements of optimal RA technique include the following:

l Single burr (or minimal number of burrs) with a burr-to-artery ratio of 0.5 to 0.6 (definitely less than 0.7)

l Rotational speeds of 140000 to 180000 rpm, with avoidance of decelerations of greater than 5000 rpm

l Gradual burr advancement using a pecking technique, accompanied by short ablation runs (<30 seconds)

l Pecking motion ( Figure 25, Video 1), namely a quick push-forward/pull-back movement of the Rotablator burr, avoiding crossing the entire lesion during the initial passage and avoiding slow forward movement of the burr.

l Final polishing run. ( Video 2),

Arterial access

The route of arterial access is dictated by the maximum burr size needed for adequate RA ( Table 2).

Femoral arterial access is preferred when the required sheath size is 8Fr or bigger. The radial approach has often been avoided for procedures using rotational atherectomy because of concern over the limitations on size of the guiding catheter. Indeed, because of this, radial approach has been associated with smaller burr size as compared with femoral approach. However, rotational atherectomy currently aims at lesion modification more than plaque debulking, in order to facilitate stent deployment, and therefore a guiding catheter larger than 7F is seldom used, making the radial approach perfectly feasible. Alternatively, a transradial sheathless guiding catheter (7.5F) should be used when more aggressive treatment is anticipated.

Guide selection

( Table 2) Indicates the largest burr that will pass through a given typical modern guide catheter (note that different manufacturer’s guide catheter diameters differ slightly). However, when possible it is recommended to choose one guide size larger to avoid limitations of difficult burr delivery with aortic tortuosity, poor imaging due to difficult contrast injection and poor pressure monitoring due to pressure damping by the large burr.

As with any PCI, appropriate guide selection is essential. The ideal guide catheter curves for RA are curves that do not have the abrupt primary or secondary curves of, for example, Amplatz curves. Catheters with side holes may improve flow during the procedure. Even though these are the recommendations for RA, the operator must always consider the entire PCI when selecting the guide and Amplatz-type curves can be used if required. Before RA, the vessel and lesion need to be wired, and after RA, a stent needs to be delivered. For these reasons, guides with appropriate size, support and back-up must be selected for the procedure to avoid unnecessary catheter exchanges.

Rotawire delivery

RotaWires can be used for primary wiring, but often cannot traverse the typical anatomy in which RA is required. Modern microcatheters have improved the rate of wiring success. The wire of choice is used to cross the lesion and a microcatheter used for exchange for a RotaWire. Even if a microcatheter will not cross a lesion, once a wire has crossed, the microcatheter will often allow wire exchange for a RotaWire. Microcatheter lesion crossing can be enhanced by increased guide support, guide catheter extensions, anchor balloons and special microcatheters with a screw-like action that help traverse difficult-to-cross lesions.

As a last resort, Excimer Laser Coronary Atherectomy (ELCA) can be used in conjunction with RA (the RASER technique). The ablative effects of ELCA on calcium are minimal and success relies on the ablation of more pliable tissue within the calcific lesion. It is possible, in many such cases, to create a channel using ECLA to allow microcatheter or RotaWire passage in order to facilitate RA [8080. Fernandez JP, Hobson AR, McKenzie D, Shah N, Sinha MK, Wells TA, et al. Beyond the balloon: excimer coronary laser atherectomy used alone or in combination with rotational atherectomy in the treatment of chronic total occlusions, non-crossable and non-expansible coronary lesions. EuroIntervention [Internet]. 2013 Jun 22;9(2):243–50. ][8181. McKenzie D, Talwar SJ, Jokhi P, et al. How should I treat severe coronary artery calcification when it is not possible to inflate a balloon or deliver a RotaWire?. Eurointervention. 2011;6:779–783. ][8282. Fernandez J, Hobson A, McKenzie D, Al. E. Treatment of calcific coronary stenosis with the use of excimer laser coronary atherectomy and rotational atherectomy. Int Card. 2010;2(801–806). ].

Guide wire bias refers to wire divergence from the central axis of the vessel. In certain situations, use of the stiffer wire or passage of the RotaWire through bends or tortuosity can cause wire bias, where the wire tends to hug the lesser curvature of the diseased vessel. This results in non-coaxial passage of the burr through the lesion. Wire bias may be an advantage when the burr is moved towards an eccentric plaque to improve ablation or a disadvantage when the burr is moved closer to the vessel wall with an increased risk of dissection or perforation. Guide wire bias tends to apply stretch to elastic tissue, rendering it inelastic thereby eliminating differential cutting and increasing the risk of ablating normal tissue. A smaller burr should be selected when there is guidewire bias. Guide wire bias can be improved by changing the distal wire position or by manipulating the angle of the guide catheter. The Extra support wire is more prone to create wire bias than the floppy Rotawire.

Burr selection

Burrs are available in the following sizes: 1.25mm, 1.5mm, 1.75mm, 2.0mm, 2.15mm, 2.25mm, 2.38mm and 2.5mm. Adequate ablation and lesion modification is achieved with a burr: artery ratio of <0.7. However, there are circumstances where still smaller burrs should be chosen, at least as the initial burr, to promote safety. When the lesion can be crossed with a guidewire but not with a balloon or microcatheter, a 1.25mm burr should be the initial burr to avoid excessive heat and long ablation runs to decrease the risk of distal embolisation. A 1.25mm burr should be used as the first burr in patients with poor ejection fraction where any degree of slow flow may compromise the patient. In lesions on bends, tortuous anatomy, eccentric lesions and cases of wire bias, a smaller starting burr should be chosen. In these cases, the behaviour of the burr is a little unpredictable and it is best to test the performance with a smaller burr to avoid dissection or perforation.

Burrs larger than 1.75mm are seldom used today but occasionally a larger burr is required in very large vessels where the residual lumen can be larger than 1.75mm making the burr ineffectual. Generally, if a burr has met with significant resistance when ablating the lesion, an adequately sized burr has been reached.

Pharmacology

Patients undergoing rotational atherectomy are commonly pre-treated with dual antiplatelet therapy with aspirin (300 mg) and clopidogrel (300 mg to 600 mg) (or other Thienopyridine) at least 6 hours before the procedure. At the time of the procedure, unfractionated heparin (target ACT: > 300 sec) or Bivalirudin is administered. Although it could be used, there is no previous experience with low molecular weight heparin (LMWH) during rotational atherectomy in the published literature. Occurrence of distal embolisation and no-reflow is a serious complication which might potentially occur during rotational atherectomy. Indeed, no-reflow induces regional impairment in myocardial contractility, potentially compromising overall left ventricular function, especially in patients already affected by chronic congestive heart failure. Distal embolisation of pulverised plaque, coronary spasm and platelet activation may all contribute to the pathogenesis of this complication. The vasospastic component of the no-reflow is commonly prevented with continuous flushing through the Rotablator sheath of a drug cocktail containing heparin (10-18 U/ml), isosorbide dinitrate (5 μg/ml) and verapamil (10 μg/ml). Cocktails with nicorandil (24μg/ml) have demonstrated superior efficacy as compared to cocktails with verapamil in two small randomised studies, yet it is less commonly used [8383. Tsubokawa A, Ueda K, Sakamoto H, Iwase T, Tamaki S. Effect of Intracoronary Nicorandil Administration on Preventing No-Reflow / Slow Flow Phenomenon. 2002;66(December):1119–23. ][8484. Iwasaki K, Samukawa M, Furukawa H. Comparison of the Effects of Nicorandil Versus Verapamil on the Incidence of Slow Flow/No Reflow During Rotational Atherectomy. Am J Cardiol. 2006;98:1354–6. ][8585. Matsuo H, Watanabe S, Watanabe T, Warita S, Kojima T, Hirose T, et al. Prevention of no-reflow/slow-flow phenomenon during rotational atherectomy--a prospective randomized study comparing intracoronary continuous infusion of verapamil and nicorandil. Am Hear J. 2007;154(5):94.e1-6 ]. In case of no-reflow, in spite of the continuous flushing with the cocktail, single or repeated intracoronary boluses of substances like nitro-glycerine (100-200μg), adenosine (100-200μg), verapamil (250μg) or nitroprusside (25μg) can be administered according to heart rate and blood pressure. These drugs should be administered via a microcatheter directly into the target vessel affected by slow flow. If administered via the guiding catheter they will likely flow into branches with normal flow and be ineffectual. Hypotension potentiates slow flow and therefore IV boluses of phenylephrine (100-200μg) may be needed to keep systolic blood pressure above 100mmHg.

The spinning burr, by interacting with the vessel wall as well as with blood components, creates a sheer force, which is a function of burr size, rotational speed, and burr-to-artery ratio. Therefore, rotational atherectomy may induce platelet activation and formation of platelet aggregates. Speed reduction of RA results in a significant reduction in the size and quantity of activated platelets. Abciximab reduces transient hypoperfusion observed during RA and peri-procedural myocardial infarction [8686. Koch KC, Vom Dahl J, Kleinhans E, Klues HG, Radke PW, Ninnemann S, et al. Influence of a platelet GPIIb/IIIa receptor antagonist on myocardial hypoperfusion during rotational atherectomy as assessed by myocardial Tc-99m Sestamibi scintigraphy. J Am Coll Cardiol. 1999;33(4):998–1004. ]. In spite of this, use of IIb/IIIa inhibitors during RA is not uniform, ranging from 0 to 45% of cases depending upon the operator’s discretion. This reluctance is, in part, explained by an increased confidence of operators in performing very complex procedure with effective dual antiplatelet therapy involving aspirin and clopidogrel. This attitude is also supported by the relatively low incidence of periprocedural thrombotic events, most often represented by non-Q-wave myocardial infarction (ranging from 1.3% to 6.6%), irrespective of the use of IIb/IIIa inhibitors [8787. Khattab A a., Otto A, Hochadel M, Toelg R, Geist V, Richardt G. Drug-eluting stents versus bare metal stents following rotational atherectomy for heavily calcified coronary lesions: Late angiographic and clinical follow-up results. J Interv Cardiol. 2007;20(2):100–6. ][8888. Tsuchikane E, Suzuki T, Asakura Y, Oda H, Ueda K, Tanaka T, et al. Debulking of chronic coronary total occlusions with rotational or directional atherectomy before stenting: Final results of DOCTORS study. Int J Cardiol [Internet]. 2008;125(3):397–403. ].

Newer platelet inhibitors (prasugrel and ticagrelor) have demonstrated a superior pharmacological and clinical profile than clopidogrel, and might be a more effective alternative in preventing platelet activation induced by rotational atherectomy [5555. Windecker S, Kolh P, Alfonso F, Collet J-P, Cremer J, Falk V, et al. 2014 ESC/EACTS Guidelines on myocardial revascularization: The Task Force on Myocardial Revascularization of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) Developed with the special contribution. Eur J Cardiothorac Surg [Internet]. 2014 Aug 29 [cited 2014 Sep 2];46(August):517–92. ][8989. Wallentin L, Becker RC, Budaj A, Cannon CP, Emanuelsson H, Held C, et al. Ticagrelor versus clopidogrel in patients with acute coronary syndromes. N Engl J Med. 2009;361(11):1045–57. ][9090. Wiviott SD, Braunwald E, McCabe CH, Montalescot G, Ruzyllo W, Gottlieb S, et al. Prasugrel versus clopidogrel in patients with acute coronary syndromes. N Engl J Med [Internet]. 2007 Nov 15;357(20):2001–15. ].

Pacing

A prophylactic temporary pacemaker has often been used with RA of the right coronary artery or left circumflex (especially if dominant) to protect against the risk of temporary complete atrio-ventricular (AV) block. With the RA techniques described above, the frequency of RA related AV-block has reduced substantially, making the practice of prophylactic pacing much less common even in dominant right coronary arteries [9191. Mitar MD, Ratner S, Lavi S. Heart Block and Temporary Pacing During Rotational Atherectomy. Can J Cardiol [Internet]. 2015;31(3):335–40. ].

Procedural check list

The recommended detailed procedural checklist for The Rotablator^TM rotational atherectomy system (Boston Scientific Corporation, Natick, Boston, MA, USA) is available here www.bostonscientific.com [9292. https://www.bostonscientific. com/en-EU/products/atherectomy-systems/rotablator-rotational-atherectomy-system/rotablator ].

In summary, it entails the following key steps:

l System setup

Connect the console and switch on the power. Ensure that the air supply hose is connected to compressed air or nitrogen, with a minimum of 500psi in the tank, with 90-110psi flowing to the console. For the original console, ensure that the DynaGlide foot pedal hoses are connected (green and blue hoses are connected to the back of the console, with the pink hose connected to the front). From the advancer, connect the fibre optic tachometer cables and the air-line to the front of the console. Add RotaGlide Lubricant (optional) to a pressurised 1 litre bag of sterile saline and connect it to the advancer infusion port. Ensure that saline is dripping from the catheter sheath tip and beneath the advancer.

l Pre-procedure system test

This takes place before the burr is inserted into the guide catheter, and follows the mnemonic D.R.A.W.

Check that there is sufficient Drip from the catheter sheath tip and beneath the advancer. Set the required burr speed and check the Rotation of the burr. Ensure that there is free movement of the Advancer. Check that the Wire is visible (out of advancer and well positioned in the distal vessel on fluoroscopy).

Burr positioning

Lock the advancer knob 1cm forward before advancing into the guide catheter. Then, advance the burr forward while affixing the wire. If difficulty is encountered while advancing the burr, friction can be reduced by a very brief tap on the foot pedal (original console). Alternatively, the burr can be advanced through the guide catheter in DynaGlide mode with the brake defeat button depressed. Once the burr is in the vessel, position it proximal to the lesion and relieve any forward tension on the drive shaft by unlocking the advancer knob and pulling it back. This step is not required if the burr is advanced on DynaGlide

Ablation procedure

Advance the burr in a pecking motion until all the way through the lesion, maintaining RPM’s within 5000 of the selected platform speed. Never stop the rotations in the lesion until it has been fully ablated.

Exchange procedure

Activate the DynaGlide mode by pressing the DynaGlide button. Press the brake defeat on the advancer while an assistant advances the guide wire thereby maintaining guide wire position and the burr is pushed backward out of the guiding catheter.

RA for specific lesions

Chronic total occlusions (CTO)

Recent improvements in guidewire technology have resulted in increased primary crossing rates. However, patients with CTO still have restenosis rates up to 10% with PTCA and DES use [9393. Rubartelli P, Petronio AS, Guiducci V, Sganzerla P, Bolognese L, Galli M, et al. Comparison of sirolimus-eluting and bare metal stent for treatment of patients with total coronary occlusions: results of the GISSOC II-GISE multicentre randomized trial. Eur Heart J [Internet]. 2010 Aug;31(16):2014–20. ][9494. Colmenarez H, Escaned J, Fernández C, Lobo L, Cano S, del Angel J, et al. Efficacy and safety of drug-eluting stents in chronic total coronary occlusion recanalization: a systematic review and meta-analysis. Am Coll Cardiol. 2010;55:1854–66. ]. RA has been evaluated in the treatment of CTO both in randomised trials and observational studies.

In randomised trials there was no benefit in using RA as the first-line strategy, suggesting that RA can be used as a second-line method if the conventional techniques are unsuccessful [8888. Tsuchikane E, Suzuki T, Asakura Y, Oda H, Ueda K, Tanaka T, et al. Debulking of chronic coronary total occlusions with rotational or directional atherectomy before stenting: Final results of DOCTORS study. Int J Cardiol [Internet]. 2008;125(3):397–403. ][9595. Danchin N, Cassagnes J, Juilkre Y, Machecourt J, Bassand J, Lablanche J, et al. Balloon angioplasty versus rotational angioplasty in chronic coronary occlusions (the BAROCCO study). J Am Coll Cardiol. 1995;75:330–4. ].

Case series evaluating the utility of RA-DES for resistant CTO (i.e. guidewire could cross the lesion, but no device could be advanced over the wire through the occluded segment), showed that RA was a safe and helpful technique (RA success rate of 92.6%) [9696. Wen S, Yu H, Wang B, Sun Z, Wang M, Liu S, et al. [Feasibility and outcome of rotational atherectomy for treating resistant chronic total occlusions]. Zhonghua Xin Xue Guan Bing Za Zhi [Internet]. 2013 Jun;41(6):466–9. ].

In-stent restenosis (ISR)

The likely benefits of RA for ISR depend on the mechanism of restenosis. RA would be more beneficial if ISR was secondary to pure intimal hyperplasia, rather than underexpansion of the stent, and this possibly explains the discrepancy between the two main trials evaluating RA for ISR.

Studies of RA for ISR were performed in the pre-DES and pre-DEB (drug eluting balloon) era and the data is therefore of little significance today. DES and DEB have been demonstrated to be the most effective treatment strategy for in-stent restenosis [9797. Stone GW, Ellis SG, O’Shaughnessy CD, Martin SL, Satler L, McGarry T, et al. Paclitaxel-eluting stents vs vascular brachytherapy for in-stent restenosis within bare-metal stents: the TAXUS V ISR randomized trial. JAMA. 2006;295:1253–63. ][9898. Holmes DR, Teirstein P, Satler L, Sketch M, O’Malley J, Popma JJ, et al. Sirolimus-eluting stents vs vascular brachytherapy for in-stent restenosis within bare-metal stents: the SISR randomized trial. JAMA. 2006;295:1264–73. ][9999. Scheller B, Hehrlein C, Bocksch W, Rutsch W, Haghi D, Dietz U, et al. Treatment of coronary in-stent restenosis with a paclitaxel-coated balloon catheter. N Engl J Med. 2006;355(20):2113–24. ].The historic data for using RA in ISR has yielded mixed and inconclusive results. Therefore RA is not recommended for routine use in ISR but should be used as an enabling tool [100100. Goldberg SL, Berger P, Cohen DJ, Shawl F, Buchbinder M, Fortuna R, et al. Rotational atherectomy or balloon angioplasty in the treatment of intra-stent restenosis: BARASTER multicenter registry. Catheter Cardiovasc Interv. 2000;51(July):407–13. ][101101. Vom Dahl J, Dietz U, Haager PK, Silber S, Niccoli L, Buettner HJ, et al. Rotational atherectomy does not reduce recurrent in-stent restenosis: Results of the angioplasty versus rotational atherectomy for treatment of diffuse in-stent restenosis trial (ARTIST). Circulation. 2002;105:583–8. ][102102. Dietz U, Rupprecht HJ ürgen, De Belder MA, Wijns W, Quarles Van Ufford MA, Klues HG, et al. Angiographic analysis of the angioplasty versus rotational atherectomy for the treatment of diffuse in-stent restenosis trial (ARTIST). Am J Cardiol. 2002;90(02):843–7. ][103103. Sharma SK, Kini A, Mehran R, Lansky A, Kobayashi Y, Marmur JD. Randomized trial of Rotational Atherectomy Versus Balloon Angioplasty for Diffuse In-stent Restenosis (ROSTER). Am Heart J. 2004 Jan;147(1):16–22. ][104104. Wasiak J, Law J, Watson P, Spinks A. Percutaneous transluminal rotational atherectomy for coronary artery disease. Cochrane database Syst Rev [Internet]. 2012;12:CD003334. ].

Ostial lesions

PCI of both aorto-ostial and non-aorto-ostial lesions are associated with higher rate of procedural complications and restenosis. Nonrandomised trials suggest that RA is safe and beneficial for improving procedural and clinical success when managing calcified ostial lesions [107107. Popma JJ, Brogan WC, Pichard AD, Satler LF, Kent KM, Mintz GS, et al. Rotational coronary atherectomy of ostial stenoses. Am J Cardiol [Internet]. 1993 Feb 15;71(5):436–8. ].

Bifurcations

Mechanical debulking prior to stenting of bifurcation lesions has been proposed to prevent plaque shifting to achieve increased side branch patency. The few non-randomised studies specifically investigating the role of rotational atherectomy of both the main branch and the side branch have shown encouraging results. However, having been performed in the BMS era, these are of little applicability today [108108. Nageh T, Kulkarni NM, Thomas MR. High-speed rotational atherectomy in the treatment of bifurcation-type coronary lesions. Cardiology. 2001;95:198–205. ][109109. Dauerman HL, Higgins PJ, Sparano AM, Gibson CM, Garber GR, Carrozza JP, et al. Mechanical debulking versus balloon angioplasty for the treatment of true bifurcation lesions. J Am Coll Cardiol. 1998;32:1845–52. ][110110. Lassen JF, Holm NR, Stankovic G. Percutaneous coronary intervention for coronary bifurcation disease : consensus from the first 10 years of the European Bifurcation Club meetings. EuroIntervention. 2014;10(5):545–60. ]. Selection of RA in bifurcations should be based on the same criteria as for non-bifurcations (i.e. based on the degree of calcification). In contemporary practice, RA has been shown to perform equally well in bifurcation lesions as in non-bifurcations in terms of safety and efficacy [111111. Chambers JW, Warner C, Cortez J, Behrens AN, Wrede DT, Martinsen BJ. Outcomes after Atherectomy Treatment of Severely Calcified Coronary Bifurcation Lesions: A Single Center Experience. Cardiovasc Revasc Med [Internet]. 2019;20(7):569–72. ].

Although not routinely applied in bifurcation lesions, rotational atherectomy of the main branch before stent implantation might be an option to enable a single-stenting strategy even in the presence of eccentric, calcified plaque which might potentially jeopardise the side branch. However, this potential application still needs to be demonstrated.

RA may facilitate primary side branch wiring when difficulty is encountered due to a large plaque burden in the main vessel inhibiting manipulation of a guidewire into the side branch. Debulking the main vessel creates space for wire manipulation.

Jailed stents

Placement of a stent across a side branch may preclude access to that side branch in the future. The traditional treatment of jailed side branches is balloon angioplasty. Sometimes, it may not be possible to pass a balloon or a stent to the jailed vessel despite being able to pass a coronary wire.

As mentioned above, RA has the ability to ablate inelastic stent metal, and has been shown in numerous case reports to be relatively safe and effective but such procedures should be performed by expert operators.

Prevention and Management of Complications

RA is associated with the same spectrum of clinical complications as in PCI, including in-hospital deaths (0.6%), tamponade (0.64%), and emergent surgery (0.18%) [113113. Sakakura K, Inohara T, Kohsaka S, Amano T, Uemura S, Ishii H, et al. Incidence and Determinants of Complications in Rotational Atherectomy: Insights From the National Clinical Data (J-PCI Registry). Circ Cardiovasc Interv [Internet]. 2016;9(11). ]. Other complications include dissection, perforation, acute vessel closure, side branch loss, vasospasm, and slow flow / no reflow. In addition, a complication specifically associated with RA is burr entrapment. In general, all RA complications are reduced by meticulous adherence to the RA procedure outlined above.

Burr and catheter size

Selecting smaller burr sizes (burr: artery ratio <0.7) reduces angiographic complications without compromising procedural success. There is a lower rise in cardiac enzymes (CKMB fraction), and smaller burrs permit smaller guide catheter and arterial sheath use, with resultant fewer vascular complications. It also allows for radial rather than femoral access, without compromise to procedural success, time, and patient radiation exposure. Cautious burr selection is required in situations of uncrossable lesions, tortuosity, eccentric lesions, wire bias and clinically precarious patients.

Slow-flow/ No-reflow

Slow flow or no flow occurs secondary to distal embolisation of atherosclerotic debris, and associated thrombi, as well as vasospasm ( Video 3, Video 4). Adhering to the suggested RA technique reduces the risk of slow flow / no reflow. Specifically, alternating short burr passages with pauses, allows intermittent blood flow through the ablated coronary artery. This improves washout of the debris, and potentially reduces heat generation and vessel spasm, and therefore thrombus formation. Pharmacological strategies to prevent this phenomenon (discussed earlier under pharmacology) include adequate antiplatelet therapy and vasodilators.

When slow or no flow occurs it must be distinguished from dissection. Further burr upsizing should not be done, and balloon dilatation may be needed to establish if no flow is on a mechanical basis. Delivery of drugs to relieve slow / no flow should be performed via a microcatheter to achieve drug delivery to the appropriate vascular bed rather than via the guiding catheter. Nitroglycerine, adenosine, verapamil and nicorandil may be used [8383. Tsubokawa A, Ueda K, Sakamoto H, Iwase T, Tamaki S. Effect of Intracoronary Nicorandil Administration on Preventing No-Reflow / Slow Flow Phenomenon. 2002;66(December):1119–23. ]. Systolic blood pressure should be maintained with intravenous boluses of phenylephrine, and reflex bradycardia may require pacing to maintain an adequate perfusion pressure. Occasionally intra-aortic balloon pump insertion may be needed.

Burr entrapment

Burr entrapment might occur in the cases of aggressive advancement of the burr through very eccentric and extremely calcified lesions ( Video 5, Video 6, Video 7, Video 8). If the burr passes distal to an incompletely ablated lesion, proximal retrieval of the burr is restricted by the absence of diamond chips on the back surface of the burr. This prevents retrograde ablation. Again, this complication can be avoided by meticulous RA technique and smaller burr sizes. The burr should be rotating throughout its passage through the lesions, preventing decelerations of more than 5000rpm. Warning signs of impending burr entrapment include lack of smooth advancement under fluoroscopy, change in auditory pitch with variations in resistance encountered by the burr, or the tactile feel of resistance in the advancer knob with or without excessive driveshaft vibration.

Attempts to restart the burr should be avoided. Most times steady controlled traction on the drive shaft will release the burr. Care must be taken not to apply too much force. Be aware of the risk of proximal dissection from deep guide catheter intubation. Sometimes a second arterial access site is required. Entrapped burrs may be retrieved by balloon angioplasty. A burr might be freed with careful and slow advancement of a second guide wire (through a second guiding catheter) beyond the entrapped burr, sometimes with the help of a buddy balloon ( Video 6, Video 7,).

If catheter based strategies fail, surgical removal and CABG may rarely be required [114114. Sulimov DS, Abdel-Wahab M, Toelg R, Kassner G, Geist V, Richardt G. Stuck rotablator: The nightmare of rotational atherectomy. EuroIntervention. 2013;9:251–8. ]. ( Figure 26)

Wire fracture or entrapment

Wire fracture ( Figure 27) with or without distal entrapment of the wire can occur during RA. The transition between the distal radio-opaque portion and the stiffer shaft of the floppy Rota guidewire is susceptible to fracture. The burr will not pass beyond this transition from the 0.009” wire to 0.014” tip, and this zone should be avoided during burring in order to prevent tip separation. Operators should take caution not to bend or kink any portion of the wire (especially portions of the wire upon which RA is to be performed).

Either a microcatheter or an over-the-wire balloon can be advanced up to the point of entrapment, followed by an attempt to free the wire by exerting a vigorous pull-back. With persistent entrapment, the guidewire can be broken, and residual wire left in place, usually without major consequences.

Perforation

Perforation is one of the most feared complications of RA. It is rare if appropriate caution is exercised. The risk is greatest with larger burr : artery ratio, eccentric lesions and in angulated segments. Other risks are when the burr must be delivered through tortuous anatomy and when there is unfavourable wire bias. Management is the same as for perforation during conventional PCI including prolonged balloon dilatation and coronary covered stent graft implantation [114114. Sulimov DS, Abdel-Wahab M, Toelg R, Kassner G, Geist V, Richardt G. Stuck rotablator: The nightmare of rotational atherectomy. EuroIntervention. 2013;9:251–8. ]. It is thus essential to have a range of covered stents in the cathlab if RA is to be performed. Example of coronary perforation after RA ( Video 9, Video 10).

NOVEL (OFF-LABEL) USES

Acute Coronary Syndrome

The use of RA in acute STEMI is a relative contraindication due to the theoretical high risk of no-reflow when used in a highly thrombotic lesion [115115. van Gaal WJ, Banning AP. Percutaneous coronary intervention and the no-reflow phenomenon. Expert Rev Cardiovasc Ther [Internet]. 2007;5(4):715–31. ]. However, case reports and anecdotal evidence demonstrates successful implementation of RA in patients with a STEMI and a complex calcified culprit lesion, with a resultant increase in off-label use [116116. Sakakura K, Ako J, Wada H, Naito R, Funayama H, Arao K, et al. Comparison of frequency of complications with on-label versus off-label use of rotational atherectomy. Am J Cardiol [Internet]. 2012;110(4):498–501. ]. Data from a large STEMI registry in Poland found that when RA was required during STEMI, the procedural success was similar to that in stable RA cases and the procedural complication rates were no different to STEMI cases where RA was not required [117117. Januszek R, Siudak Z, Dziewierz A, Rakowski T, Legutko J, Dudek D, et al. Bailout rotational atherectomy in patients with myocardial infarction is not associated with an increased periprocedural complication rate or poorer angiographic outcomes in comparison to elective procedures (from the ORPKI Polish National Registry 2015-2. Postep w Kardiol interwencyjnej = Adv Interv Cardiol [Internet]. 2018;14(2):135–43. ].

A study of contemporary RA use in ACS (mainly NSTE-ACS) demonstrated similar procedural success, procedural complication rates and in-hospital MACE compared to stable cases. The long term (24 month) higher MACE in ACS patients was thought to reflect the generally worse prognosis in ACS patients compared to stable cases [118118. Allali A, Abdelghani M, Mankerious N, Abdel-Wahab M, Richardt G, Toelg R. Feasibility and clinical outcome of rotational atherectomy in patients presenting with an acute coronary syndrome. Catheter Cardiovasc Interv [Internet]. 2019;93(3):382–9. ]. Other reports have shown similar findings [119119. Kübler P, Zimoch W, Kosowski M, Tomasiewicz B, Telichowski A, Reczuch K. Acute coronary syndrome - Still a valid contraindication to perform rotational atherectomy? Early and one-year outcomes. J Cardiol [Internet]. 2018;71(4):382–8. ].

Unprotected Left Main Disease

RA to calcified unprotected left main lesions can achieve high procedural success with low complication rates. This has been demonstrated in both case reports and series. Attention to meticulous technique, with appropriate burr size selection is the key to minimising complications [120120. Chiang MH, Yi HT, Tsao CR, Chang WC, Su CS, Liu TJ, et al. Rotablation in the treatment of high-risk patients with heavily calcified left-main coronary lesions. Journal of Geriatric Cardiology. 2013. p.217–25 ][121121. Yabushita H, Takagi K, Tahara S, Fujino Y, Warisawa T, Kawamoto H, et al. Impact of Rotational Atherectomy on Heavily Calcified, Unprotected Left Main Disease. Circ J [Internet]. 2014;78(August):1867–72. ].

Saphenous Vein Grafts

Calcified saphenous vein grafts have been treated successfully with RA. It is important to distinguish calcification from thrombus before this is undertaken with the assistance of intracoronary imaging if needed. Conservative burr selection and careful methodology is advised [122122. Pellicano M, Floré V, Barbato E, De Bruyne B. From debulking to delivery: sequential use of rotational atherectomy and GuidezillaTM for complex saphenous vein grafts intervention. BMC Cardiovasc Disord [Internet]. 2018;18(1):122. ]. Video 11 demonstrates RA of severe calcified in-stent restenosis within a proximal vein graft where the lesion could not be crossed with low profile coronary balloons.

Dissected Vessels

After failed attempts at dilating a calcified lesion, there may be dissection in the vessel. Whilst this is a relative contraindication, there are numerous instances where RA has been employed successfully in rescuing the vessel and allowing procedure completion. Newer technologies such as intracoronary lithotripsy may, however, prove more prudent in such situations in the future.

Subintimal Ablation

Occasionally, when using antegrade dissection techniques for navigating the subintimal space during CTO PCI, significant subintimal calcification impedes progress. There are case reports of successful subintimal RA [123123. Capretti G, Carlino M, Colombo A, Azzalini L. Rotational atherectomy in the subadventitial space to allow safe and successful chronic total occlusion recanalization: Pushing the limit further. Catheter Cardiovasc Interv [Internet]. 2018;91(1):47–52. ]. This should only be performed by highly experienced operators and only with a 1.25mm burr. Example of ablation in LAD sub-intimal space ( Video 12, Video 13).

Guide extension use with RA

Guide extensions has been used to aid RA. Extreme vessel tortuosity with angulations >90⁰ is seen as a contraindication to RA due to risk of complications such as burr stall, vessel perforation or wire fracture. In the event of extreme vessel tortuosity proximal to a calcified lesion, a guide extension can be advanced beyond the tortuous segment and allow small burr sizes to passed safely to the calcified lesion [124124. Kato T, Fujino M, Takagi K, Noguchi T. The rotational atherectomy with a guide extension catheter for calcified and tortuous lesions in left anterior descending artery: a case report. BMC Cardiovasc Disord [Internet]. 2021;21(1):360. ].

SUMMARY – Rotational Atherectomy

RA is an invaluable tool for lesion modification, enabling successful deployment of stents in calcified coronary lesions. This technology broadens the treatment horizon, allowing safe treatment of complex coronary anatomy which would otherwise be impossible to safely manage by PCI. Adherence to appropriate procedural technique achieves a high rate of procedural success with low complication rates.

ORBITAL ATHERECTOMY SYSTEM (OAS)

The Diamondback 360°® System (Cardiovascular Systems, Inc., St Paul, MN, USA) ( Figure 28, Figure 29) is an orbital atherectomy system (OAS) that has been shown to be safe and effective for the management of calcified coronary lesions, with a stent delivery success rate of 98% and adverse outcomes (including Q-wave MI, cardiac death, and target vessel revascularisation) of less than 1% [125125. Parikh K, Chandra P, Choksi N, Khanna P, Chambers J. Safety and feasibility of orbital atherectomy for the treatment of calcified coronary lesions. Catheter Cardiovasc Interv [Internet]. 2013;81(October 2012):1134–9. ][126126. Chambers JW, Feldman RL, Himmelstein SI, Bhatheja R, Villa AE, Strickman NE, et al. Pivotal trial to evaluate the safety and efficacy of the orbital atherectomy system in treating de Novo, severely calcified coronary lesions (ORBIT II). JACC Cardiovasc Interv [Internet]. 2014;7(5):510–8. ].

The Diamondback 360°® System uses the elliptical movement of a single-sized mounted crown to differentially sand the calcified component of the plaque while sparring softer tissues. A drive shaft with an eccentrically mounted diamond-coated crown rotates at two set speeds of 80,000 or 120,000 rpm. Rotation is powered by high-pressure air or nitrogen, similar to that used for rotational atherectomy. Once in the artery, the crown may be advanced forwards and backwards using the handle. The system operates on the principles of centrifugal force. Centrifugal force (F_C) is proportional to the mass of the rotating object (m) and the square of the velocity of rotation (v²) and is inversely proportional to the radius of the orbit: F_C = (mv²)/R. As the crown rotates and the orbit increases, centrifugal force presses the crown against the lesion or plaque, removing plaque with each orbit. The diamond-grit coating on the orbital atherectomy crown pulverises the plaque as the device comes into contact with the wall. Softer tissue flexes away from the crown while fibrotic tissue or calcium is engaged and ablated. In addition, pulsatile forces may indirectly impact deeper calcification. OAS fractures calcified lesions, thereby increasing lesion compliance and facilitating stent expansion [127127. Shlofmitz E, Martinsen BJ, Lee M, Rao S V, Généreux P, Higgins J, et al. Orbital atherectomy for the treatment of severely calcified coronary lesions: evidence, technique, and best practices. Expert Rev Med Devices [Internet]. 2017 Nov;14(11):867–79. ][128128. Kini AS, Vengrenyuk Y, Pena J, Motoyama S, Feig JE, Meelu OA, et al. Optical coherence tomography assessment of the mechanistic effects of rotational and orbital atherectomy in severely calcified coronary lesions. Catheter Cardiovasc Interv [Internet]. 2015 Nov 15;86(6):1024–32. ].

The specificity of orbital atherectomy is the variable lumen size which can be created by each device. Since centrifugal force is a function of both the mass of the device and the speed of rotation, faster speeds result in increased centrifugal force, yielding a larger orbit. As a result, a larger lumen can be created with a given crown simply by rotating it at higher speeds. Only a single crown is needed. Increasing the duration of ablation, the number of passes, or the rotational speed increases luminal gain. The elliptical orbit allows blood and debris to flow past the crown, thus continually flushing the vessel and cooling the crown, thereby minimising thermal injury and slow flow [129129. Chambers JW, Diage T. Evaluation of the Diamondback 360 Coronary Orbital Atherectomy System for treating de novo, severely calcified lesions. Expert Rev Med Devices [Internet]. 2014 Sep;11(5):457–66. ]. The average particle size created by OAS is 2.04μm; 98.3% of particles are smaller than a red blood cell; and 99.2% of particles are smaller than the diameter of a capillary [127127. Shlofmitz E, Martinsen BJ, Lee M, Rao S V, Généreux P, Higgins J, et al. Orbital atherectomy for the treatment of severely calcified coronary lesions: evidence, technique, and best practices. Expert Rev Med Devices [Internet]. 2017 Nov;14(11):867–79. ].

Data supporting use of orbital atherectomy system (OAS)

The original ORBIT I trial evaluated the safety and performance of OA in fifty patients with de novo calcified lesions, and showed both safety and efficacy in changing the compliance of calcified lesions to facilitate stent placement [130130. Parikh K, Chandra P, Choksi N, Khanna P, Chambers J. Safety and feasibility of orbital atherectomy for the treatment of calcified coronary lesions: the ORBIT I trial. Catheter Cardiovasc Interv [Internet]. 2013 Jun 1;81(7):1134–9. ]. The ORBIT II pivotal trial enrolled 443 patients with severely calcified de-novo coronary stenotic lesions. Stents were successfully delivered in 97.7% of patients. Orbital atherectomy (OA) was safe with 30-day freedom from MACE of 89.6%. OAS was therefore effective and safe. A low TLR following DES implantation was maintained out to 3 years [126126. Chambers JW, Feldman RL, Himmelstein SI, Bhatheja R, Villa AE, Strickman NE, et al. Pivotal trial to evaluate the safety and efficacy of the orbital atherectomy system in treating de Novo, severely calcified coronary lesions (ORBIT II). JACC Cardiovasc Interv [Internet]. 2014;7(5):510–8. ][131131. Lee M, Généreux P, Shlofmitz R, Phillipson D, Anose BM, Martinsen BJ, et al. Orbital atherectomy for treating de novo, severely calcified coronary lesions: 3-year results of the pivotal ORBIT II trial. Cardiovasc Revasc Med [Internet]. 2017 Jun;18(4):261–4. ]. Subsequent registry data corroborated the efficacy and safety of OAS with low rates of procedural complications (dissection, perforation, and slow flow all below 1%) and low rates of 30-day clinical events. These results were confirmed in real world registry data of over 400 patients showing excellent 1-year results [132132. Lee MS, Shlofmitz E, Goldberg A, Shlofmitz R. Multicenter Registry of Real-World Patients With Severely Calcified Coronary Lesions Undergoing Orbital Atherectomy: 1-Year Outcomes. J Invasive Cardiol [Internet]. 2018;30(4):121–4. ].

The Coronary Orbital Atherectomy System Study (COAST) evaluated the latest upgrade of the OA system, the Diamondback 360 Micro Crown. This newer version has a new diamond-coated tip designed to better reach target lesions, with a 1.25mm eccentric crown allowing for rotation at slower speeds (50 000 to 70 000rpm). The study showed that 85% of patients were MACE-free at 30 days [133133. Coronary Orbital Atherectomy System Study (COAST). [Internet]. 2014. ].

The currently recruiting ECLIPSE trial (Clinicaltrials.gov identifier NCT03108456, estimated completion end 2024) is enrolling patients with severe calcification, comparing orbital atherectomy preparation to conventional PCI in terms of stent expansion and TVF. The trial is the largest randomized coronary atherectomy trial to date, incorporating post-procedural OCT evaluation, and is powered to demonstrate superiority of OAS vessel preparation.

While the initially results have all been positive, the Manufacturer and User Facility Device Experience (MAUDE) database showed that in real-world practice there were a number of perforations related to excessive straightening of the ViperWire [134134. Khalid N, Javed H, Rogers T, Hashim H, Shlofmitz E, Wermers JP, et al. Adverse events with orbital atherectomy: an analytic review of the MAUDE database. EuroIntervention [Internet]. 2020 Jul 17;16(4):e325–7. ]. This may be avoided by refining the techniques used (see below).

Components of the orbital atherectomy system

Viper Wire

The ViperWire guide wire is a 0.012” stainless steel wire, with a silicone coating and a radiopaque distal spring tip. It is torquable and can be used to cross lesions and for subsequent stent delivery but if there is any difficulty, primary wiring can be performed with the operator’s preferred wire which must be subsequently exchanged for the ViperWire using a microcatheter. The wire should be placed as distal as possible and remain in the main branch. During OA, the tip of the device must avoid contact with the spring tip of the ViperWire to avoid wire tip damage or fracture.

Viper Slide

Viper Slide is a combination of vasodilator and anticoagulation drugs that is used to lubricate and flush coronaries during OA to reduce adverse events. 20 ml of Viper slide is mixed in a litre of saline. ViperSlide lubricant should always be continually infused during OAS operation to help minimise thermal injury.

The OAS Pump

The pump mounts on the IV pole and provides power and delivers fluid.

The Crown

The coronary classic crown is 1.25mm in diameter ( Figure 30). Varying degrees of ablation and lumen enlargement are achieved with this single crown by altering sanding times, number of passes and rotational speed. The crown has diamond coating on both the front and back surfaces, allowing atherectomy in both forward and reverse directions, thereby increasing sanding while preventing entrapment.

As mentioned previously, a coronary Micro Crown has been investigated in the COAST trial. The Micro Crown is an eccentric crown while the Classic Crown is positioned concentrically on an eccentric bump on the driveshaft ( Figure 31). This allows the OAS Micro Crown to rotate at lower speeds while creating an orbit similar to the OAS Classic Crown. The Micro Crown has a new driveshaft that contains a diamond coated tip designed to pilot through tight, severely calcified lesions. The crown is tapered with front edge sanding to enhance lesion crossability and operates at reduced speeds (50 or 80krpm).

The Handle

The handle controls the crown by means of an advancer knob which allows forward and backward movement of up to 8cm ( Figure 32). There is an on/off switch on the knob. A speed control button selects a speed of 80krpm or 120krpm.

The differences between RA and OAS

The RA burrs come in multiple sizes and spin concentrically, while the OAS crown comes in a single size and spins eccentrically in an orbit which is modifiable. The RA burr is coated only on the front end and ablates only in a forward direction, while the OAS crown ablates bidirectionally in a forward and reverse direction. RA speeds can be set anywhere between 140krpm and 200krpm, while OAS has 2 speeds: 80krpm and 120krpm.

Orbital atherectomy procedural considerations

Guiding Catheter

The OAS is 6F compatible. Coaxial alignment of the guiding catheter is important to avoid directing the crown towards the wall of the artery. Non-coaxial alignment increases the risk of angiographic complications. Extra-support guides are preferred.

Setup Procedures

Wire the lesion and then exchange for the ViperWire. Ensure a minimum of 10 mm of distance between OA device and guidewire tip during treatment. Prime the OAS and before inserting into the guide catheter, perform a momentary test spin. Open the brake, lock the control knob at the 1-cm mark and keep the pump on. Advance the crown to 3-5 mm proximal to the lesion. GlideAssist Mode (5krpm spin to facilitate insertion/removal) can be activated to advance/remove the device. Hold down the low-speed button until it begins to slowly blink. To initiate spinning in GlideAssist Mode, the on/off button is pressed to start/stop spinning. The low-speed light will rapidly blink. Once in position 5mm proximal to the lesion, press any button to switch off GlideAssist.

Performing Sanding

If the lesion is very severe, place the nose cone of the device partially into the lesion, but not fully occlusive, to facilitate crossing. Unlock the advancer knob and slide it to the 0-cm mark to relieve built-up tension/torque in the drive shaft. This process is particularly important for tortuous vessels where there is greater tension/torque buildup in the drive shaft while the device is advanced to the lesion. Failure to relieve tension/torque can result in jumping of the crown into the lesion during the initial activation.

Engage the brake and always start at low speed and traverse slowly (1–3 mm/s) to engage the lesion. Slow and steady advancement results in significantly larger luminal gain as compared to faster traverse rates with the same number of passes. Advancing the travel knob slowly will increase the radius of orbit and allow time to potentially create fractures within the calcium [135135. Sotomi Y, Shlofmitz RA, Colombo A, Serruys PW, Onuma Y. Patient Selection and Procedural Considerations for Coronary Orbital Atherectomy System. Interv Cardiol (London, England) [Internet]. 2016 May;11(1):33–8. ]. Rapid advancement (>10 mm/s) increases the risk of complications such as dissection or perforation while reducing efficacy. OAS works bi-directionally, so it is important to use the same slow movement when advancing the crown forward or backward. Watch the crown movement via fluoroscopy to ensure 1:1 movement. If 1:1 movement is lost, disengage the crown from the lesion by moving the advancer knob 1–2 mm proximally to remove tension from the drive shaft. Reengage the lesion targeting the same 1–3 mm/s traverse speed while monitoring for 1:1 movement. The orbital nature of the procedure allows the device to contact the vessel wall, resulting in continued sanding even after the entire lesion has been traversed. Continue the 1–3 mm/s traverse speed, until there is no further resistance or change in pitch during advancement. These tactile and auditory clues are used to determine if adequate ablation has been achieved.

A single run should not exceed 30 s and the total treatment time should not exceed 5 min. Always stop the device in a non-occlusive segment of the artery (do not stop in the middle of the lesion). There is a warning sound at 25 seconds. Continue slow movement until a non-occlusive segment is reached and then stop. Rest for the same duration as the last run time and ensure stable haemodynamics before reactivating the device. Do not continue to run the device in one place as this can cause localised vessel injury. Continuous crown movement is required to prevent uneven treatment and maintain safety. If the lesion is long, perform multiple shorter runs and take time to cross the lesion in smaller sections.

Always start at low speed. The speed can be increased to high speed to achieve a larger diameter of sanding in larger vessels or if resistance and pitch changes are not overcome by multiple low speed passes. Avoid high speed in angulated or tortuous segments and small vessels less than 3mm. In most cases, low speed alone is sufficient.

If, after OAS, there is inadequate balloon expansion, further OAS can be performed at low or high speed as long as no visible dissection is evident.

Temporary Pacing

Significant bradycardia is uncommon during OAS [111111. Chambers JW, Warner C, Cortez J, Behrens AN, Wrede DT, Martinsen BJ. Outcomes after Atherectomy Treatment of Severely Calcified Coronary Bifurcation Lesions: A Single Center Experience. Cardiovasc Revasc Med [Internet]. 2019;20(7):569–72. ]. If bradycardia occurs, it is mostly transient and can be minimised by shorter run times and atropine if necessary. Very occasionally, a pacing lead may be needed during treatment of long lesions in a dominant RCA or Circumflex.

Aorto-ostial lesions

OA crown rotation is less concentric (when compared to RA), so when there is a large transition from large to small lumen such as aorto-ostial lesions, an unconstrained orbit in the aorta should be avoided. This is achieved in one of two ways. First, if the device can cross the lesion, ablation should be performed retrograde (by backward movement from distal to proximal) until full ablation is achieved. Second, if the device cannot cross, the guide should be close to the lesion and coaxial to allow engagement of the nose cone into the lesion. After the first pass, the remainder of the procedure should be completed retrograde.

SUMMARY – Orbital Atherectomy

OAS is lesion modifying technology that enables treatment of calcified coronary lesions which would otherwise be untreatable or carry high risk with conventional PCI. OAS has the specificity of allowing bi-directional atherectomy and control of the degree of ablation of calcium and of the achieved luminal diameter prior to stenting. Like RA, attention to meticulous procedural technique is the key to effective safe utilisation of OAS.

INTRACORONARY LITHOTRIPSY

Introduction

Intravascular lithotripsy (aka Lithoplasty®) (IVL) is a novel tool that can be used for lesion preparation in calcified coronary artery lesions prior to stent implantation. As discussed earlier, RA and specialized balloons have traditionally been used for lesion preparation in these calcified lesions. Specialized balloons have limited effect in circumferential calcified lesions and non-dilatable lesions. RA is underutilized due to lack of operator experience, the level of technical difficulty and the risk of complications, especially with low volume operators. Furthermore, neither of these methods provide modification of calcium embedded deep in the vessel wall. IVL is an innovative technology, adapted from the treatment of kidney stones, for treatment of calcified arterial disease. IVL makes use of a traditional balloon catheter with multiple emitters implanted in the catheter within the mounted balloon segment. These emitters produce high-speed sonic pressure waves that pass through soft tissue and result in significant shear stress to selectively fracture intimal and medial calcium within the vessel wall.

The use of IVL was first described in the treatment of calcified peripheral artery lesions [136136. Brodmann M, Werner M, Brinton TJ, Illindala U, Lansky A, Jaff MR, et al. Safety and Performance of Lithoplasty for Treatment of Calcified Peripheral Artery Lesions. J Am Coll Cardiol [Internet]. 2017;70(7):908–10. ]. Subsequently, as the safety and efficacy of this technology was shown in peripheral arteries, the use of IVL has expanded to the treatment of calcified coronary artery disease [137137. Brinton T, Al. E. EuroPCR; May 16-19, 2017; Paris. In: PCI: Procedural techniques and clinical outcomes – Session comprising selected late-breaking trial submissions. 2017. ]. IVL has received U.S. Food and Drug Administration (FDA) approved IVL for calcified peripheral arteries in 2017 and for coronary use in 2021. IVL gained European CE mark in May 2017 for treatment of coronary artery disease.

Data supporting the use of IVL

The DISRUPT CAD I single arm study enrolled 60 patients were with severely calcified lesions (≤ 32mm length) in a native coronary artery. Device success was 98%. Stenting was performed in 86.7% of cases. Clinical success (residual stenosis <50% without in-hospital MACE) was 95%. At 30 days the cumulative MACE rate was 5%. There were no cardiac deaths, Q-wave MIs or target vessel revascularizations at 30 days. Procedural safety was achieved with no complications such as coronary dissections, perforations abrupt vessel closure, slow flow or no reflow. In an OCT sub-study of 31 patients, there was an average acute gain of minimal luminal area of 3.7mm [138138. Brinton T, Ali Z, Di Mario C, Al. E. Performance of the lithoplasty system in treating calcified coronary lesions prior to stenting: results from the DISRUPT CAD OCT sub-study. J Am Coll Cardiol. 2017;69(11 Supplement):1121. ].

The DISRUPT CAD II single arm trail enrolled 120 patients with severe calcified major coronary artery disease to be treated with IVL and stenting [139139. Ali ZA, Nef H, Escaned J, Werner N, Banning AP, Hill JM, et al. Safety and Effectiveness of Coronary Intravascular Lithotripsy for Treatment of Severely Calcified Coronary Stenoses: The Disrupt CAD II Study. Circ Cardiovasc Interv [Internet]. 2019;12(10):e008434. ]. Device success was achieved in all patients. The composite primary end point of in-hospital MACE (cardiac death, myocardial infarction and target vessel revascularization) occurred in 5.8% of patients. 7 patients had non-Q-wave myocardial infarctions. There was no procedural abrupt closure, slow or no reflow, or perforations following IVL. In 47 patients with post-PCI OCT, calcium fracture was identified in 78.7% of lesions with 3.4±2.6 fractures per lesion.

The Disrupt CAD III prospective, single-arm multicenter study was designed for regulatory approval of coronary IVL [140140. Hill JM, Kereiakes DJ, Shlofmitz RA, Klein AJ, Riley RF, Price MJ, et al. Intravascular Lithotripsy for Treatment of Severely Calcified Coronary Artery Disease. J Am Coll Cardiol [Internet]. 2020;76(22):2635–46. ]. 431 patients with severe coronary calcification were enrolled and had IVL and stenting. An OCT sub study was also performed to assess the mechanism of calcium modification. The primary safety endpoint of freedom from MACE at 30 days occurred in 92.2%. Procedural success was achieved in 92.4%. 67.4% of lesions demonstrated multiplane and longitudinal calcium fractures after IVL as assessed with OCT. Stent expansion post IVL was similar between lesions that had not demonstrated fractures OCT compared to lesions that had fractures seen on OCT.

A pooled analysis was performed of the DISRUPT CAD trials, including the DISRUPT CAD IV trial (72 patients study for regulatory approval in Japan) [141141. Kereiakes DJ, Di Mario C, Riley RF, Fajadet J, Shlofmitz RA, Saito S, et al. Intravascular Lithotripsy for Treatment of Calcified Coronary Lesions: Patient-Level Pooled Analysis of the Disrupt CAD Studies. JACC Cardiovasc Interv [Internet]. 2021;14(12):1337–48. ]. Cumulative safety and effectiveness of coronary IVL was assessed. The primary safety endpoint of freedom from MACE at 30 days was achieved in 92.7%. The primary effectiveness endpoint of procedural success (stent delivery with a residual stenosis ≤30% by quantitative coronary angiography without in-hospital major adverse cardiovascular events) was achieved in 92.4%. The rates of target lesion failure, cardiac death, and stent thrombosis were 7.2%, 0.5%, and 0.8% at 30 days. Serious angiographic procedural complications were low with no post-IVL associated perforations, abrupt closure, or episodes of no reflow.

Components of IVL

Intravascular Lithotripsy (IVL) (Shockwave Medical Inc. Fremont, CA, USA) consists of three main components: IVL catheters, IVL connector cables and an IVL generator ( Figure 33).

The IVL catheter has miniaturized lithotripsy emitters enclosed in an integrated angioplasty balloon mounted on a rapid exchange system ( Figure 34). These emitters produce pulsatile energy transmitted through the length and diameter of the mounted balloon. The catheter has radiopaque markers to guide positioning in the coronaries. It can be delivered via a 6 French or greater coronary guide catheter. All the coronary IVL catheters are mounted with a 12mm length balloon in seven balloon sizes varying from 2.5mm to 4.0mm in diameter with increments of 0.25mm. The inflation port and emitter cable that attach to the connector cable are situated at the rear of the catheter.

The IVL connector cable has a front handle that connects to the IVL catheter ( Figure 35). This handle also houses the therapy button. When pressed this button activates the lithotripsy sonic pulse waves. A connection port is situated at the rear of the connector cable that directly plugs in to the IVL generator.

The IVL generator is a rechargeable battery powered generator that links to the balloon catheter via a connector cable ( Figure 36). Prior to delivery of IVL treatment there are no settings or adjustments required, as an integrated chip in the catheter provides pre-set lithotripsy delivery parameters.

Each Shockwave balloon can deliver a total of 80 pulses in bursts of 10 pulses at 1 pulse per second.

Procedural considerations for IVL

As with coronary balloon angioplasty, firstly a 0.014” coronary guidewire is passed distal to the calcified coronary lesion. Preparation of the IVL catheter is performed by connecting a balloon indeflator (filled with a 1:1 mix of saline and contrast) to the inflation port. The IVL catheter balloon should then be prepared and de-aired like conventional coronary balloons. Particular attention should be applied to the de-airing procedure since air in the balloon reduces the effectiveness of the IVL therapy. The connector cable is placed within a sterile sleeve and attached to the catheter emitter cable. The coronary guidewire is then threaded through the IVL catheter rapid exchange system and the catheter is then advanced over the guidewire to the coronary artery. The radiopaque markers on the catheter are used to position the catheter in the calcified coronary lesion. Then the catheter balloon is inflated to 4 atmospheres pressure to allow contact to the vessel wall to optimise energy delivery of the sonic pulse waves ( Video 14). The therapy control button on the connector cable is then pressed, and held, to activate a treatment cycle consisting of one pulse per second for 10 seconds. Following every cycle, the balloon can optionally be inflated to 6 atmospheres of pressure. This may help to compress the fractured calcium prior to a new treatment cycle. A maximum of 8 treatment cycles can be delivered per IVL catheter to obtain adequate vessel expansion prior to stent implantation. For lesions longer than 12mm the catheter has to be repositioned to treat the length of the lesion. In lesions requiring more than 8 treatment cycles, a second IVL catheter would need to be used. In the rare event that the IVL catheter is not able to initially cross a calcified lesion, pre-dilation with low profile angioplasty balloons could be performed or even rotational atherectomy may be used to facilitate IVL catheter delivery. Following IVL therapy, a conventional PCI approach is adopted with stent implantation and optimisation at the operator’s discretion.

A hybrid approach between rotational atherectomy and IVL can also be performed. The hybrid approach would be ideal in large caliber vessels with deep calcification and critical stenosis not allowing balloon passage. This would involve performing rotational atherectomy with a small burr size (1.25mm) to create a channel to allow an IVL catheter balloon to be passed through the calcified lesion. IVL would then be performed with the aim at optimal modification of deep/thick calcium prior to stent implantation.

NOVEL (OFF-LABEL) USE

Stent underexpansion

In the event of a stent that cannot be expanded following deployment despite high pressure post dilation with NC balloons, there are several bailout options. Firstly, post dilation of the stent can be performed with ultra-high-pressure balloons that can be inflated to ≥ 40atm pressure. Although off-label, IVL has been reported to safely and effectively treat undilatable stents. The SMILE registry reported the feasibility and safe such use of IVL [142142. Ielasi A, Moscarella E, Testa L, Gioffrè G, Morabito G, Cortese B, et al. IntravaScular Lithotripsy for the Management of UndILatable Coronary StEnt: The SMILE Registry. Cardiovasc Revasc Med [Internet]. 2020;21(12):1555–9. ]. The recently published CRUNCH registry also demonstrated the ability of IVL to significantly improve stent expansion in previously underexpanded stents. In most cases adjunctive high pressure balloon inflation was added to IVL and a small number of patients had additional stent implantation [143143. Tovar Forero MN, Sardella G, Salvi N, Cortese B, di Palma G, Werner N, et al. Coronary lithotripsy for the treatment of underexpanded stents; the international multicentre CRUNCH registry. EuroIntervention [Internet]. 2022 Mar 23. ].

Stentablation or “rototripsy” has also been described as a bailout treatment for under-expanded stents. This was described before the advent of IVL. This involves rotational atherectomy through the newly deployed stent followed by 2^nd stent deployment. While there are reports of success, stentablation may lead to distal embolization of metal particles, burr entrapment in the stent and excessive heat generation [144144. Whiteside HL, Nagabandi A, Kapoor D. Safety and Efficacy of Stentablation with Rotational Atherectomy for the Management of Underexpanded and Undilatable Coronary Stents. Cardiovasc Revasc Med [Internet]. 2019 Nov;20(11):985–9. ] and may still not adequately ablate deeper calcium. It is likely that such an approach would seldom if ever be needed in the era of IVL.

Under-expanded and undilatable stents pose a high risk for in-stent thrombosis and acute myocardial infarction and despite being an off-label use, we regard IVL as the treatment of choice for under-expanded and undilatable stents. Figure 37 demonstrates a case of an un-expandable stent despite the use of ultra-high-pressure balloons at pressures of 48 atmospheres. IVL was successfully used to improve lesion compliance resulting in expansion of the stent.

SUMMARY – Intracoronary Lithotripsy

IVL creates calcium microfractures, enhancing vessel compliance and allowing adequate dilatation of calcified lesions. It has the specificity of treating both superficial and deep calcium. Unlike other technologies such as RA or OAS, it’s use is very similar to conventional PCI, making it relatively easy to learn and implement. Recent data has confirmed IVL as an effective coronary calcification modifying tool with high procedural effectiveness and low rates of procedural complications.

ALGORITHMIC APPROACH TO THE DIAGNOSIS AND MANAGEMENT OF CORONARY CALCIFICATION

To clarify how to choose the appropriate first calcium modifying tool we propose an algorithmic approach to decision making. Several authors have proposed algorithms to guide treatment of coronary calcification [145145. De Maria GL, Scarsini R, Banning AP. Management of Calcific Coronary Artery Lesions: Is it Time to Change Our Interventional Therapeutic Approach. JACC Cardiovasc Interv [Internet]. 2019;12(15):1465–78. ][146146. Ueki Y, Otsuka T, Hibi K, Räber L. The Value of Intracoronary Imaging and Coronary Physiology When Treating Calcified Lesions. Interv Cardiol (London, England) [Internet]. 2019 Nov;14(3):164–8. ][147147. Oksnes A, McEntegart M. Intravascular Lithotripsy to Modify Calcified Coronary Artery Disease. How to use the Shockwave coronary Rx lithotripsy system. Card Interv Today. 2020; September/. ]. Since PCI in heavily calcified coronary lesions caries an increased risk of periprocedural complications, a clear indication for PCI needs to be established before embarking on a PCI strategy. Once the indication for PCI has been established, careful evaluation of the lesion is required to plan the appropriateness of calcium modification as the first step in PCI. Consideration needs to be given to the severity of calcification, anatomical characteristics, and the operator needs to assess the likely ability to deliver microcatheters, balloons or calcium modifying devices up to and across the lesion.

Assessment of coronary calcification severity:

Fluoroscopy

fluoroscopic evidence for severe calcification is the finding of dense radiopacities noted without cardiac motion before contrast injection, and seen on both sides of the vessel

When calcium is seen on fluoroscopy but does not fulfill the criteria for severe calcification or the operator is uncertain of the severity of calcification, additional intravascular imaging (IVUS or OCT) to further evaluate calcium severity, is strongly advised.

Intravascular imaging (IVUS or OCT)

Mild to moderate calcification: arc of calcium < 270⁰ and length of the calcified lesion <5mm.

Severe calcification: arc of calcium > 270⁰ and length of the calcified lesion >5mm and thickness of ≥0.5mm (thickness can only be seen by OCT).

In the event that the IVUS or OCT catheter cannot cross the lesion, it can be assumed that calcification is severe.

Assessment of lesion and vessel characteristics:

Lesion and vessel characteristics are evaluated to determine the most appropriate calcium modification tool for calcium modification prior to stent implantation. The reference size of the vessel, minimal luminal size at the stenosis, length of the lesion, eccentricity and nodularity of calcium, relation of the lesion to large side branches and tortuosity or angulation of the lesion and the ability of a balloon to cross the lesion all may influence the choice of the calcium modification tool to be used.

Lesions where IVL is favored:

• Large vessels with residual minimal luminal diameters ≥2mm. Even with the largest burr sizes, rotational atherectomy may not modify the lesion significantly and in this instance IVL should be the preferred choice.
• In lesions with a calcium thickness of ≥0.5mm, IVL may also be favored due to its ability to modify deep calcium as opposed to rotational atherectomy which may only ablate superficial calcium.
• Lesions involving bifurcations such as the distal LMS, IVL has the advantage of not having to remove a coronary wire from the side branch.
• In extreme tortuosity or angulation rotational atherectomy may be contraindicated due to the risk of burr stall, perforation, or wire fracture.

Lesions where atherectomy is favored:

• The smallest IVL catheter is 2.5mm, therefore IVL cannot be used in vessels smaller than 2.5mm.
• In diffuse long lesions, atherectomy may be preferred as the whole length of the lesion can be modified with the use of one burr as opposed to using multiple IVL catheter balloons.
• In eccentric and nodular calcified lesions, especially where wire bias will favor contact of the burr tip with the calcium, rotational atherectomy will be appropriate.
• In lesions where a balloon cannot cross the lesion, rotational atherectomy should be chosen.

In the rare event of being unable to deliver a rota-wire through a lesion, laser atherectomy can be considered to modify the lesion entry.

In moderate sized vessels, moderate length lesions and in multi-vessel calcified disease (with different vessel sizes), IVL or atherectomy may be used based on operator preference and cost considerations.

Algorithm

Our proposed algorithm for the assessment and management of calcified coronary disease is designed from a practical perspective, illustrated in Figure 38, and involves 5 steps.

Step 1: establish the indication for PCI.

Step 2: quantify the severity calcification. If there is fluoroscopic ambiguity, use of intravascular imaging (IVUS or OCT).

Step 3: Use the appropriate calcium modification tool(s). Mild to moderate eccentric calcified lesion can be predilated with non-compliant, cutting or scoring balloons at nominal pressures. Severe calcified lesions need upfront IVL, rotational atherectomy (or orbital atherectomy). Evaluation of the anatomy of the lesion determines the appropriate choice between IVL and rotational atherectomy.

Step 4: evaluate the compliance of the lesion by performing dilatation with a non-compliant balloon sized 1:1 to the distal vessel reference size. This allows evaluation of the effectiveness of calcium modification prior to stent implantation. If the non-compliant (NC) balloon does not fully expand, or has noticeable waist, then further modification of the lesion is required. An alternative is to repeat intra-vascular imaging. Finding several visible fractures in the calcium is a marker of successful calcium modification but fractures are not always seen even if adequate lesion preparation has been achieved. Balloon dilatation should always be performed prior to stenting.

Step 5: stent implantation (or DCB angioplasty) and evaluation of the result, ideally by intravascular imaging.

Conclusion

The percutaneous management of complex coronary artery disease is becoming more frequent. Cardiologists are currently expected to meet the demands of an older population of patients with more extensive coronary disease and multiple comorbidities. Being able to offer these patients safe, effective percutaneous solutions is an essential component of interventional cardiology.

Percutaneous rotational atherectomy has up to now been the most effective and safest method for enabling PCI in calcific coronaries. With increased education and training, RA has become firmly established as an essential tool for all interventional cardiologists. Structured training and proctorship are essential for the acquiring the expertise needed to be proficient at RA. This should be a goal for all interventional training programs. Best outcomes are seen with proficiency of the entire cath lab staff (not just the interventionalist), appropriate patient selection, correct equipment selection and meticulous technique.

The challenge of treating ever more calcified lesions has spurned the development of other newer technologies such as orbital atherectomy and intracoronary lithotripsy. These, as well as the upgraded new RA console and advancer, may enable more operators to treat a broader range of this important subset of patients as a routine in the cathlab.

Personal perspective - Farrel Hellig

My personal experience in treating significant coronary calcification is with rotational atherectomy. I performed my first procedure in 1999 after having had the privilege of being proctored by John Lasala from St Louis, USA. This proctorship was highly influential for my career as it gave me insight into the essential role of plaque modification in enabling successful, safe treatment of complex coronary lesions. Subsequently I have performed thousands of RA procedures.

What I have learned over this period is that many cases simply cannot be treated without RA or other calcium modifying tool. As a rule, I favour a low threshold for utilising such enabling technologies because I am convinced that they make PCI much safer, more effective and more efficient with less fluoroscopy and contrast use, when significant calcium is present.

The cathlab should designate an operator who’s goal it should be to achieve a high level of proficiency in calcium modifying techniques. The industry partners producing these tools have been highly responsible in their management of training, and they have established a well worked pathway of online training, proctorship and mentorship to take new operators through the initial steps and up to independence. What is important is that the technologies are utilised with adequate frequency so that the entire cathlab team remains familiar and at ease with these tools.

The ideal goal is to reach a situation where, at any moment, a tool such as rotational atherectomy could be seamlessly integrated into a PCI procedure and performed ad-hoc without any disruption to cathlab workflow. This requires a permanent installation which is checked daily at the beginning of a cath list and all cathlab staff to be accustomed to the procedure, so as to work as an integrated team.

Many patients today are elderly and have co-morbidities and are therefore ineligible for coronary bypass surgery. When their lifestyle is severely limited by symptoms despite optimal medical therapy, PCI is the only remaining option. These clinical situations go hand-in-hand with coronary calcium and as a result there is a rapidly growing need for cath lab competency in the therapies discussed this chapter. Use of these techniques is extremely rewarding for both patients and operators. They often enable safe PCI of what are otherwise impossible-to-treat lesions and can produce dramatic symptom relief and quality of life improvements.

Lesion modifying tools are used in a as little as 5% of procedures despite significant calcification being present in 32% of cathlab patients [77. Mori H, Torii S, Kutyna M, Sakamoto A, Finn A V, Virmani R. Coronary Artery Calcification and its Progression: What Does it Really Mean? JACC Cardiovasc Imaging [Internet]. 2018;11(1):127–42. ]. It is my hope that the recent improvements in rotational atherectomy technology as well as the newer therapeutic modalities discussed in this chapter will result in far more frequent use of these enabling tools to the benefit of our patients.