Intravascular lithotripsy in chronic total occlusion percutaneous coronary intervention

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.

Impact of calcium on the procedural techniques and outcomes of chronic total occlusion percutaneous coronary intervention

BACKGROUND

Coronary calcification is common and increases the difficulty of chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

METHODS

We examined the impact of calcium on procedural outcomes of 13,079 CTO PCIs performed in 12,799 patients at 46 US and non-US centers between 2012 and 2023.

RESULTS

Moderate or severe calcification was present in 46.6% of CTO lesions. Patients whose lesions were calcified were older and more likely to have had prior coronary artery bypass graft surgery. Calcified lesions were more complex with higher J-CTO score (3.0 ± 1.1 vs. 1.9 ± 1.2; p < 0.001) and lower technical (83.0% vs. 89.9%; p < 0.001) and procedural (81.0% vs. 89.1%; p < 0.001) success rates compared with mildly calcified or non-calcified CTO lesions. The retrograde approach was more commonly used among cases with moderate/severe calcification (40.3% vs. 23.5%; p < 0.001). Balloon angioplasty (76.6%) was the most common lesion preparation technique for calcified lesions, followed by rotational atherectomy (7.3%), laser atherectomy (3.4%) and, intravascular lithotripsy (3.4%). The incidence of major adverse cardiovascular events (MACE) was higher in cases with moderate or severe calcification (3.0% vs. 1.2%; p < 0.001), as was the incidence of perforation (6.5% vs. 3.4%; p < 0.001). On multivariable analysis, the presence of moderate/severe calcification was independently associated with lower technical success (odds ratio, OR = 0.73, 95% CI: 0.63-0.84) and higher MACE (OR = 2.33, 95% CI: 1.66-3.27).

CONCLUSIONS

Moderate/severe calcification was present in nearly half of CTO lesions, and was associated with higher utilization of the retrograde approach, lower technical and procedural success rates, and higher incidence of in-hospital MACE.

The Impact of Calcium on Chronic Total Occlusion Management

Coronary artery calcification is prevalent in chronic total occlusions (CTO), particularly in those of longer duration and post-coronary artery bypass. The presence of calcium predicts lower procedural success rates and a higher risk of complications of CTO percutaneous coronary intervention. Adjunctive imaging, including pre-procedural computed tomography and intracoronary imaging, are useful to understand the distribution and morphology of the calcium. Specialised guidewires and microcatheters, as well as penetration, subintimal entry and luminal re-entry techniques, are required to cross calcific CTOs. The use of both atherectomy devices and balloon-based calcium modification tools has been reported during CTO percutaneous coronary intervention, although they are limited by concerns regarding safety and efficacy in the subintimal space.

Intravascular Lithotripsy for Calcium Modification in Chronic Total Occlusion Percutaneous Coronary Intervention

Intravascular lithotripsy (IVL) has been shown to be safe and effective for calcium modification in nonocclusive coronary artery disease (CAD), but there are only case reports of its use in calcified chronic total occlusions (CTO). We report data from an international multicenter registry of IVL use during CTO percutaneous coronary intervention (PCI) and provide provisional data regarding its efficacy and safety. During the study period, IVL was used in 55 of 1053 (5.2%) CTO PCI procedures. IVL was used within the occluded segment after successful CTO crossing in 53 procedures and during incomplete CTO crossing in 2 cases. The mean J-CTO score was 3.1. CTO PCI technical and procedural success was achieved in 53 (96%) and 51 (93%) cases. Six patients had a procedural complication, with 3 main vessel perforations (5%). Two had covered stent implantation, one required pericardiocentesis, and one was managed conservatively. All had combination therapy with another calcium modification device. Two patients had a procedural myocardial infarction (PMI) (4%), and two others had a major adverse cardiovascular event (MACE) (4%) at a median follow-up of 13 (4–21) months. IVL can effectively facilitate calcium modification during CTO PCI. More data are required to establish the efficacy and safety of IVL and other calcium modification devices when used extraplaque or in combination during CTO PCI.

Coronary lithotripsy: a novel approach to intra-coronary calcification with 'cracking' results?

Coronary lithotripsy is a novel approach to percutaneous coronary intervention (PCI). It is based on well-established technology dating back to 1980 when lithotripsy was first used to treat renal calculi. Its application in cardiovascular medicine is a more recent development that involves using a low-pressure lithotripsy balloon to deliver unfocused acoustic pulse waves in a circumferential mechanical energy distribution. This causes fracturing of calcification within the surrounding vasculature, facilitating optimal stent deployment. This article aims to review recent clinical experience and the published data regarding intravascular lithotripsy (IVL). All relevant articles were identified via PubMed using keywords including "intravascular lithotripsy", "shockwave" and "coronary". All studies that contained published datasets regarding IVL with patient numbers >50 were included for review. There were 116 results found. After reviewing all the publications, articles were then tabulated and 17 were found to be relevant, including only four clinical studies. In this review we found that intracoronary lithotripsy for heavily calcified arteries appears to be a safe, effective, easy-to-use method of dealing with an otherwise technically-challenging and high-risk scenario. It appears to carry low risk, uses low pressures, and exerts its effects on both superficial and deep intravascular calcium. Further prospective data with long-term follow-up will be required to explore both the off-label uses of IVL (such as post-stent dilatation), and the long-term patency of these vessels.

Latest developments in chronic total occlusion percutaneous coronary intervention

INTRODUCTION

Chronic Total Occlusion Percutaneous Coronary Intervention (CTO PCI) is now performed with high success rates and acceptable complication rates.

AREAS COVERED

We describe recent clinical and technological developments in CTO PCI from 2018 to 2020.

EXPERT OPINION

After publication of six randomized controlled trials, improving patient symptoms remains the principal indication for CTO PCI. Although good outcomes can be achieved with CTO PCI at experienced centers, success rates are significantly lower at less experienced centers, despite increased use in CTO crossing algorithms and development of novel and improved equipment and techniques.

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).