Combined Rotational Atherectomy and Intravascular Lithotripsy for the Treatment of Severely Calcified in-Stent Neoatherosclerosis: A Mini-Review

Intravascular lithotripsy in coronary arteries: a review of case reports

BACKGROUND

Calcified coronary arteries encountered during percutaneous intervention increase the probability of unsuccessful procedures. Heavy calcification of coronary arteries may lead to suboptimal stent expansion. Intravascular lithotripsy (IVL) is a novel method of transmitting sonic waves in pulses, which fractures the calcific plaque in the vessel with minimal soft tissue injury. This study systematically reviews and summarizes the reported clinical scenarios in which IVL was successfully used in coronary lesions.

MAIN TEXT

Articles were obtained by searching PubMed and Embase databases for IVL use in coronary arteries. We restricted the search to case reports. Our study included 84 patients from 70 case reports/case series. The mean age was 70.3 years (SD 10) and ranged from 27 to 96 years, and 67% were males. The indications for the angiogram that led to the use of IVL include chest pain (37.7%), non-ST elevated myocardial infarction (27.9%), ST elevated myocardial infarction (13.1%), and previous under-expanded stent (8.2%). The IVL was used in the left anterior descending artery (60.7%), right coronary artery (35.7%), left main disease (23.8%), and left circumflex (9.5%). Coronary IVL was safely and successfully used in different clinical scenarios for heavily calcified coronary lesions, including in-stent restenosis of native coronary arteries, saphenous vein grafts, and under-expanded stents. In addition, IVL was successfully used synergistically with orbital and rotational atherectomy and drug-coated balloon angioplasty in select patients.

CONCLUSION

IVL has successfully been used in an expanding array of clinical scenarios.

Dedicated Balloon Techniques for Coronary Calcium Modification

Coronary calcification represents a significant technical challenge in percutaneous coronary intervention and is associated with worse clinical outcomes. Fortunately, a number of balloon-assisted technologies are available to aid in the management of coronary calcification before stenting. Adequate lesion preparation is crucial in the successful management of calcified coronary lesions. Balloon-based techniques can be a safe and effective method of lesion preparation and, as such, are an integral part of an interventionalist's armamentarium. In this mini-review, we focus on the use of non-compliant balloons, super high-pressure non-compliant balloons, cutting balloons, scoring balloons and intravascular lithotripsy.

In-Stent Restenosis Overview: From Intravascular Imaging to Optimal Percutaneous Coronary Intervention Management

Despite ongoing progress in stent technology and deployment techniques, in-stent restenosis (ISR) still remains a major issue following percutaneous coronary intervention (PCI) and accounts for 10.6% of all interventions in the United States. With the continuous rise in ISR risk factors such as obesity and diabetes, along with an increase in the treatment of complex lesions with high-risk percutaneous coronary intervention (CHIP), a substantial growth in ISR burden is expected. This review aims to provide insight into the mechanisms, classification, and management of ISR, with a focus on exploring innovative approaches to tackle this complication comprehensively, along with a special section addressing the approach to complex calcified lesions.

Coronary intravascular lithotripsy in contemporary practice: challenges and opportunities in coronary intervention

Percutaneous coronary intervention (PCI) of calcified coronary arteries is associated with poor outcomes. Poorly modified calcified lesion hinders the stent delivery, disrupts drug-carrying polymer, impairs drug elution kinetics and results in under-expanded stent (UES). UES is the most common cause of acute stent thrombosis and in-stent restenosis after PCI of calcified lesions. Angiography has poor sensitivity for recognition and quantification of coronary calcium, thereby mandating the use of intravascular imaging. Intravascular imaging, like intravascular ultrasound and optical coherence tomography, has the potential to accurately identify and quantify the coronary calcium and to guide appropriate modification device before stent placement. Available options for the modification of calcified plaque include modified balloons (cutting balloon, scoring balloon and high-pressure balloon), atherectomy devices (rotational atherectomy and orbital atherectomy) and laser atherectomy. Coronary intravascular lithotripsy (IVL) is the newest addition to the tool box for calcified plaque modification. It produces the acoustic shockwaves, which interact with the coronary calcium to cause multiplanar fractures. These calcium fractures increase the vessel compliance and result in desirable minimum stent areas. Coronary IVL has established its safety and efficacy for calcified lesion in series of Disrupt CAD trials. Its advantages over atherectomy devices include ease of use on workhorse wire, ability to modify deep calcium, no debris embolization causing slow flow or no-flow and minimal thermal injury. It is showing promising results in modification of difficult calcified lesion subsets such as calcified nodule, calcified left main bifurcation lesions and chronic total occlusion. In this review, authors will summarize the mechanism of action for IVL, its role in contemporary practice, evidence available for its use, its advantages over atherectomy devices and its imaging insight in different calcified lesion scenarios.

Intravascular lithotripsy for severe coronary calcification: a systematic review

INTRODUCTION

Coronary artery calcification remains a challenge in percutaneous coronary interventions, due to the higher risk of suboptimal result with subsequent poor clinical outcomes. Intravascular lithotripsy is a novel way of treating severe coronary calcification as it has the ability to modify calcium both circumferentially as well as transmurally, facilitating stent expansion and apposition. We conducted a systematic overview of the published literature on intravascular lithotripsy (IVL) assessing the efficacy and feasibility of IVL in treating severe coronary calcification.

EVIDENCE ACQUISITION

Of the retrieved publications, 62 met our inclusion criteria and were included. A total of 1389 patients (1414 lesions) with significant coronary calcification or under-expanded stents underwent IVL.

EVIDENCE SYNTHESIS

The mean age was 72.03 years (74.7% male). There was a significant improvement in acute and sustained vessel patency, with mean minimal lumen diameter of 2.78±0.46 mm, resulting in acute gain of 1.72±0.51 mm. The acute procedural success rate was 78.2 to 100% with in-hospital complication rate of 5.6 to 7.0%. The majority of the studies reported 30-day MACE, which was between 2.2 to 7.8%.

CONCLUSIONS

The recent studies have highlighted that the use of IVL with adjuvant intracoronary imaging has revolutionized the way of treating heavily calcified, non-dilatable coronary lesions and is likely to succeed the conventional ways of treating these complex lesions. We need further studies to gauge the long-term efficacy and safety of IVL against techniques currently available for calcium modification including conventional balloons, cutting or scoring balloons, rotational atherectomy and laser atherectomy.

Rotational atherectomy of calcified coronary lesions: current practice and insights from two randomized trials

With growing experience, technical improvements and use of newer generation drug-eluting stents (DES), recent data showed satisfactory acute and long-term results after rotational atherectomy (RA) in calcified coronary lesions. The randomized ROTAXUS and PREPARE-CALC trials compared RA to balloon-based strategies in two different time periods in the DES era. In this manuscript, we assessed the technical evolution in RA practice from a pooled analysis of the RA groups of both trials and established a link to further recent literature. Furthermore, we sought to summarize and analyze the available experience with RA in different patient and lesion subsets, and propose recommendations to improve RA practice. We also illustrated the combination of RA with other methods of lesion preparation. Finally, based on the available evidence, we propose a simple and practical approach to treat severely calcified lesions.

SCAI Expert Consensus Statement on Management of In-Stent Restenosis and Stent Thrombosis

Stent failure remains the major drawback to the use of coronary stents as a revascularization strategy. Recent advances in imaging have substantially improved our understanding of the mechanisms underlying these occurrences, which have in common numerous clinical risk factors and mechanical elements at the time of stent implantation. In-stent restenosis remains a common clinical problem despite numerous improvements in-stent design and polymer coatings over the past 2 decades. It generates significant health care cost and is associated with an increased risk of death and rehospitalization. Stent thrombosis causes abrupt closure of the stented artery and therefore carries a high risk of myocardial infarction and death. This Society for Cardiovascular Angiography & Interventions (SCAI) Expert Consensus Statement suggests updated practical algorithmic approaches to in-stent restenosis and stent thrombosis. A pragmatic outline of assessment and management of patients presenting with stent failure is presented. A new SCAI classification that is time-sensitive with mechanistic implications of in-stent restenosis is proposed. Emphasis is placed on frequent use of intracoronary imaging and assessment of timing to determine the precise etiology because that information is crucial to guide selection of the best treatment option. SCAI recommends image-guided coronary stenting at the time of initial implantation to minimize the occurrence of stent failure. When in-stent restenosis and stent thrombosis are encountered, imaging should be strongly considered to optimize the subsequent approach.

Prevalence and patterns of in-stent neoatherosclerosis in lower extremity artery disease

BACKGROUND

In-stent restenosis (ISR) is responsible for a rapid decline of vessel patency after stenting. To date, little is known about the role of in-stent neoatherosclerosis (NA) in stent failure in lower limb arteries.

AIMS

This study aimed to determine the prevalence and patterns of in-stent NA in patients with symptomatic ISR of the lower extremity vasculature using intravascular optical coherence tomography (OCT) imaging.

METHODS

Patients underwent endovascular revascularisation for ISR including angiography and OCT imaging. NA was defined as the presence of at least 1 fibroatheroma or fibrocalcific plaque within the neointima of a stented segment.

RESULTS

Using OCT, we imaged 24 symptomatic patients with lower extremity artery disease (LEAD), with a total of 30 ISR in the lower limbs, prior to their scheduled endovascular interventions. NA formation was observed in 23 (76.7%) lesions, while all stents with an implant duration >5 years (n=8) showed signs of NA. The time from stent implantation to OCT was significantly increased in lesions with NA (p=0.002). Lesions without NA had a significantly shorter duration from index procedure to OCT than those with ≥50 percent (n=9; p=0.003) or <50 percent (n=14; p=0.015) of frames exhibiting signs of NA. NA was predominantly characterised by fibroatheroma with thick fibrous caps with or without calcification.

CONCLUSIONS

In-stent NA is frequently identified by OCT imaging after endovascular therapy in lower limb arteries; this increased both in frequency and extent the longer the duration since implantation. Our findings indicate an active atherosclerotic process that may need tailored mitigation strategies.

Intravascular Imaging for Guiding In-Stent Restenosis and Stent Thrombosis Therapy

Advances in stent technology and the design of endovascular devices with thinner struts, anti-inflammatory and antithrombotic polymers, and better drug kinetics have enhanced the safety and efficacy of the second-generation drug-eluting stents and broadened their use in the therapy of high-risk patients and complex anatomies. However, despite these developments, in-stent restenosis and stent thrombosis remain the Achilles' heel of percutaneous coronary intervention, with their cumulative incidence reaching up to 10% at 5 years following percutaneous coronary intervention. The treatment of stent failure poses challenges and is associated with a worse prognosis than conventional percutaneous coronary intervention. Several studies have recently highlighted the value of intravascular imaging in identifying causes of stent failure, underscored its role in treatment planning, and registries have shown that its use may be associated with better clinical outcomes. The present review aims to summarize the evidence in the field; it discusses the value of intravascular imaging in identifying the mechanisms of in-stent restenosis and stent thrombosis in assessing the morphological characteristics of neointima tissue that appears to determine long-term outcomes in evaluating procedural results, and presents the findings of studies supporting its value in guiding therapy in stent failure.

Intravascular Lithotripsy for Treatment of Calcified Coronary Artery Disease

Intravascular lithotripsy (IVL) uses acoustic shock waves in a balloon-based delivery system to modify severely calcified atherosclerotic coronary vascular lesions in preparation for stent implantation. IVL results in circumferential and longitudinal calcium fracture, which improves transmural vessel compliance and facilitates subsequent stent expansion without requiring high-pressure balloon dilation. Clinical trials have demonstrated IVL to be safe (low rates of major adverse cardiac events in hospital and to 1 year; low rates of severe angiographic complications), effective (high rates of procedural success), and easy to use (little or no learning curve) when applied in the treatment of severely calcified coronary arteries.

Intravascular imaging in coronary stent restenosis: Prevention, characterization, and management

Despite the introduction of drug-eluting stents to combat the neointimal hyperplasia that occurred after BMS implantation, in-stent restenosis is still encountered in a significant number of patients, particularly as increasingly complex lesions are tackled by percutaneous coronary intervention. Many biological and mechanical factors interplay to produce restenosis, some of which are avoidable. Intravascular imaging provided unique insights into various forms of stent-related mechanical issues that contribute to this phenomenon. From a practical perspective, intravascular imaging can therefore help to optimize the stenting procedure to avert these issues. Moreover, once the problem of restenosis eventuates, imaging can guide the management by tackling the underlying identified mechanism. Finally, it can be used to evaluate the re-intervention results. Nevertheless, with the emergence of different treatment options, more evidence is needed to define patient/lesion-specific characteristics that may help to tailor treatment selection in a way that improves clinical outcomes.

Intravascular lithotripsy during percutaneous coronary intervention: current concepts

INTRODUCTION

Coronary artery calcification (CAC) is commonly encountered by interventional cardiologists. Severe CAC may impair stent delivery or result in stent underexpansion, stent thrombosis and/or in-stent restenosis (ISR). Multiple tools have been developed to help overcome the challenges associated with CAC and improve outcomes for these patients. Intravascular shockwave lithotripsy (IVL) is a novel therapy that uses acoustic pressure waves for the modification of CAC.

AREAS COVERED

This review discusses the growing body of evidence to support the safety and efficacy of IVL in the setting of de novo severely calcified coronary arteries prior to stenting. We also discuss international real world experience with the coronary IVL system. This includes the use of IVL in the setting of acute coronary syndrome (ACS), ISR and in combination with other tools for calcium modification.

EXPERT OPINION

IVL is a safe and effective therapy that results in the fracture of coronary calcium and facilitates optimal stent delivery and expansion. Longer term follow up is essential to shed light on the durability and late outcomes of an IVL strategy. Randomised control trials are warranted to compare IVL to alternative methods of calcium modification and to explore further the use of IVL for ACS.

Initial experience of a single referral centre using excimer laser coronary atherectomy-assisted expansion in undilatable stents: Excimer laser in undilatable stents

AIMS

Undilatable stents with severe peri-stent calcification are an important cause of target lesion failure and therapeutic options are limited. We report our initial experience with the safety and efficacy of excimer laser coronary atherectomy (ELCA)-assisted expansion of undilatable stents.

METHODS AND RESULTS

ELCA was performed with saline, blood and contrast-enhanced trains. All lesions were post-dilated at high pressures and treated with a drug-eluting balloon. Thirty-one lesions with undilatable stents were included at a single centre with experienced operators from March 2016 to February 2021. The mean number of prior procedures for in-stent restenosis was three and 14 lesions had multiple layers of stent. Procedural success (>50% increase in minimal stent diameter [MSD]) and adequate stent expansion (MSD >70% of reference vessel diameter) was achieved in all lesions. At six-month follow-up (N=26 lesions), there were six periprocedural myocardial infarctions due to slow flow, two cardiac deaths and one target lesion revascularisation. There were no perforations.

CONCLUSIONS

Our niche experience at a centre with experienced operators demonstrated that ELCA led to larger final lumen and stent dimensions in highly selected patients with undilatable stents and recurrent restenosis at the cost of relatively frequent slow flow.

Physiological and angiographic outcomes of PCI in calcified lesions after rotational atherectomy or intravascular lithotripsy

BACKGROUND

Percutaneous coronary interventions (PCI) in calcified coronary artery lesions are associated with impaired stent expansion, higher rate of periprocedural complications and cardiac mortality. Lesion preparation using calcium modifying techniques such as Rotational Atherectomy (RA) or Intravascular Lithotripsy (IVL) has been advocated. Studies comparing these technologies are lacking. We aimed to compare the in-stent pressure gradient, evaluated by virtual fractional flow-reserve, in calcific lesions treated using either RA or IVL.

METHODS

Patients undergoing either RA- or IVL-assisted PCI from two European centers were included. Propensity score matching (1:2) was performed to control for potential bias. Primary outcome was post- PCI in-stent pressure gradient calculated by virtual fractional flow reserve (vFFRgrad). Secondary outcomes included the proportion of patients with complete functional revascularization defined as of distal vFFR post PCI (vFFRpost) ≥ 0.90.

RESULTS

From a cohort of 210 patients, 105 matched patients (70 RA and 35 IVL) were included. Pre-PCI vFFR did not differ between groups (0,65 ± 0,13 RA and 0,67 ± 0,11 IVL). After PCI, in-stent pressure gradients were significantly lower in the IVL group (0.032 ± 0.026 vs 0.043 ± 0.026 in the RA group, p = 0.024). The proportions of vessels with functional complete revascularization was similar between the two groups (32.9% vs. 37.1% in the RA and IVL group, respectively; p = 0.669).

CONCLUSIONS

Calcific lesions preparation with IVL is effective and resulted in improved in-stent pressure gradient compared to RA. Approximately one third of the patients undergoing PCI for a severely calcified lesion achieved functional revascularization with no difference between rotational RA and IVL.

Is Coronary Brachytherapy Staging a Comeback for the Treatment of In-Stent Restenosis?

PURPOSE OF REVIEW

The catheter-based coronary intervention has become a well-established therapeutic modality for obstructive coronary artery disease. However, in-stent restenosis remains a significant limitation of coronary intervention despite the use of newer devices. Intravascular brachytherapy was introduced to treat recurrent in-stent restenosis but only modestly adopted. This review will discuss the mechanism of intracoronary brachytherapy, available clinical evidence of brachytherapy in recurrent in-stent restenosis treatment, and the future of coronary brachytherapy in coronary intervention.

RECENT FINDINGS

Drug-eluting stents have an inherent limitation as they leave a permanent metal layer inside an artery when deployed. Recently, drug-coated balloon technology has emerged to treat coronary artery disease as a combination of balloon angioplasty and local drug delivery without leaving a metal layer behind. Recent European guidelines recommended using drug-coated balloons when treating in-stent restenosis treatment, while the US guidelines have not yet addressed the use of drug-coated balloons in such cases. Coronary brachytherapy is a valuable addition to treat these challenging diseases despite several logistic issues. If there are newer technologies with easier setup, such as drug-coated balloons, coronary brachytherapy resurgence is improbable in the contemporary era, although it may not become obsolete.

Waksman In-Stent Restenosis Classification: A mechanism-based approach to the treatment of restenosis

Despite contemporary advances in stent technology, in-stent restenosis (ISR) remains a common issue following percutaneous coronary intervention. A novel classification system based on underlying mechanism of action of restenosis was recently introduced. The Waksman In-Stent Restenosis Classification characterizes different patterns of ISR to best delineate the type of restenosis and help guide treatment. Intravascular imaging with either intravascular ultrasound or optical coherence tomography allows for real-time evaluation of ISR. We herein provide an illustrative review of the Waksman In-Stent Restenosis Classification.

Resolving chronic stent under-expansion in calcified lesions by intravascular lithoplasty

Severe coronary calcification is a common cause for stent under-expansion, which is associated with an increased risk of stent thrombosis and restenosis. Presently the devices for treatment of under-expanded stent due to severe calcification are rotational atherectomy and high-pressure non-compliant balloons with the limitation of potential balloon rupture and perforation risk. We report on a series of seven successful treatments of chronically under-expanded stents due to severe calcification using shockwave coronary intravascular lithoplasty (IVL). Our report suggests that IVL is a feasible and safe tool for such chronically under-expanded stents. <Learning objective: Severe coronary calcification is a common cause for stent under-expansion, which is associated with an increased risk of stent thrombosis and restenosis. Presently the devices for treatment of under-expanded stent due to severe calcification are rotational atherectomy and high-pressure non-compliant balloons. Our report suggests that intravascular lithoplasty is a feasible and safe tool to expand chronically under-expanded stents due to severe calcification, and that it is superior to rotational atherectomy and high-pressure balloons.>.

Intracoronary lithotripsy for calcific neoatherosclerotic in-stent restenosis: a case report

Background

In-stent restenosis is a difficult percutaneous scenario if calcific neoatherosclerosis is the underlying aetiology.

Case summary

A 69-year-old diabetic woman with a previous percutaneous coronary intervention on the left anterior descending coronary artery was readmitted for non-ST-elevation myocardial infarction. In-stent restenosis due to calcific neoatherosclerosis was observed by intracoronary imaging during the intervention. Intravascular lithotripsy was used successfully to fracture the underlying calcific plaque. However, the balloon ruptured during treatment although this did not damage the artery.

Discussion

Intravascular lithotripsy is a promising tool for the treatment of extremely calcified lesions including calcific neoatherosclerosis of in-stent restenosis. Balloon rupture is a complication of this new percutaneous treatment that has not previously been described.

Using the coronary lithotripsy system for coronary artery disease

Severe coronary artery calcification increases percutaneous treatment complexity and the risk of intraprocedural complications, affecting acute and long-term outcomes. Current use of specialty balloons and atherectomy technologies is limited due to the higher risk of complications, degree of technical difficulty and operator experience. Intravascular lithotripsy (IVL) is a novel technology for severe calcified coronary artery disease that facilitates vessel preparation, enhancing vessel compliance. IVL system emits sonic waves that penetrate through vascular layers and disrupt both superficial and deep calcium, leaving the soft tissue unharmed. The purpose of the present review is to provide a summary of the evidence currently available on this therapy, including a practical description of the components and function of the shockwave coronary IVL system.

The Coronary Intravascular Lithotripsy System

Calcified lesions often mean percutaneous intervention results are suboptimal and increase the risk of procedural complications and future adverse events. Available plaque-modifying devices rely on tissue compression or debulking, with the intention of fracturing calcium and facilitating optimal stent deployment. In contrast, coronary intravascular lithotripsy delivers unfocused, circumferential, pulsatile mechanical energy to safely disrupt the calcium within the target lesion. The present review summarises the evidence available so far on this therapy and includes a practical description of the components and function of the Shockwave Intravascular Lithotripsy System (Shockwave Medical).