Over the past few years, the number of percutaneous coronary interventions (PCI) performed in patients with severely calcified coronary artery disease (CAD) has significantly increased [1]. Heavily calcified lesions are challenging in terms of adequate lesion preparation, equipment delivery, and optimal stent deployment [2]. Several PCI adjunctive tools for plaque modification have been introduced to deal with severely calcified lesions safely and effectively [3].
Shockwave Intravascular Lithotripsy (S-IVL) has emerged as a novel therapy for the treatment of vascular calcification [2]. The Shockwave Medical Coronary IVL catheter (Santa Clara, CA, US) consists of a 0.014-inch guidewire-compatible balloon catheter with two lithotripsy emitters incorporated into the shaft of a 12-mm-long balloon [4]. The IVL catheter is delivered, inflated, and deflated as any other balloon. During brief and low-pressure balloon inflation, 10 IVL pulses are delivered creating acoustic shockwaves that spread circumferentially and transmurally with minimal effect on soft tissue while imparting compressive stress on calcified plaques [4]. Each balloon catheter can deliver up to 80 pulses or 120 with the latest generation Shockwave C2+ system with interval deflations to allow distal coronary perfusion [4].
The safety and efficacy of the S-IVL system have been supported by the company-sponsored single-arm prospective DISRUPT CAD studies (I, II, III, and IV) [5]. In a patient-level pooled analysis of these studies reporting results from 628 patients across 72 sites in 12 countries, the primary safety (i.e., absence of in-hospital major adverse cardiovascular events) and effectiveness (i.e., procedural success) endpoints were achieved in 92.7% and 92.4% of patients, respectively [5]. At 30 days, the rates of target lesion failure, cardiac death, and stent thrombosis were 7.2%, 0.5%, and 0.8%, respectively. Rates of post-IVL and final serious angiographic complications were 2.1% and 0.3%, with no IVL-associated perforations, abrupt closures, or episodes of no reflow [5].
In this issue of Kardiologia Polska (Polish Heart Journal), Rola et al. [6] present data from the Lower Silesia Shockwave Registry (LSSR). The registry includes 131 PCI cases where the S-IVL system was used between May 2019 and September 2022 in two high-volume Polish cardiac centers. S-IVL was used either for calcium modification in resistant calcified lesions before stent deployment (76% of recruited cases) or for stent optimization in significantly underexpanded previously implanted stents (25% of cases). The study evaluated procedural success and clinical outcomes in-hospital and in 6-month follow-up. Procedural success was met in 96% of cases, with 3 cases of device failure (i.e., S-IVL balloon rupture) without clinical consequences. Regarding clinical outcomes, in-hospital MACE was 4.6% and 7.9% at 6 months.
Several clinical and procedural aspects of the study are important and add to the existing literature. Firstly, 87% of the patients presented with acute coronary syndrome (ACS) (8.4% ST-segment elevation myocardial infarction [STEMI] and 74% non-STEMI [NSTEMI]). ACS was essentially an exclusion criterion for the DISRUPT CAD studies. Nevertheless, ACS cases represent a significant part of PCI procedures in high-volume cardiac centers. Calcified culprit lesions are frequent in NSTEMI and STEMI patients undergoing urgent or emergency PCI and directly impact future target lesion failure [7, 8]. Having an easy, safe, and effective method for calcium modification is important, and the current study supports S-IVL use in this cohort.
In 1 of 4 cases in the LSS Registry, S-IVL was used to treat significant underexpansion of previously implanted stents. Although initially an “off-label” use, S-IVL for stent restenosis secondary to underexpansion became a popular strategy for this challenging clinical scenario with limited therapeutic options [9–11]. The LSSR data show that S-IVL is a relatively safe and effective approach when dealing with stent underexpansion.
The previous use of rotational or orbital atherectomy was not an exclusion criterion for the study, and 13.7% of the patients had atherectomy debulking before S-IVL use. The occasional complementary use of the 2 calcium-modifying modalities should be noted, a strategy that appeared to be safe and effective in a recently published report from the international multicenter Rota-Shock Registry [12]. Finally, the left main artery constituted 20.6% of the treated vessels in the study, adding to previous reports [13, 14] that supported S-IVL use to treat LM lesions (another exclusion criterion in the DISRUPT CAD studies).
The current study carries the inherent limitations of registry-based studies such as potential selection bias, retrospective data collection, and lack of a control group or adjudication for procedural and clinical endpoints. From a procedural perspective, the lack of universal post-dilation (applied in 77% of cases) and the relatively low use of intracoronary imaging for the specific cohort (23.7%) should be noted.
Nevertheless, the study by Rota et al. provides real-life data in a high-risk population supporting the use of S-IVL as an everyday tool for calcium modification. This kind of data are necessary for S-IVL to demonstrate its safety and efficacy outside the “sterile” environment of clinical studies where several exclusion criteria are applied. In conclusion, the Lower Silesia Shockwave Registry showed short- and long-term safety and efficacy for S-IVL in the treatment of resistant de novo calcified coronary disease and stent underexpansion. Still, the lack of comparative studies in the literature regarding S-IVL is striking. Studies comparing S-IVL with other calcium/plaque modifying techniques are needed. Furthermore, the high price of the device compared to alternative modalities, merits cost-effectiveness analysis and adequate reimbursement policies [15].
Article information
Conflict of interest: None declared.
Funding: Founded by National Science Center of Poland – grant ID# 2017/27/B/NZ5/02944.
Open access: This article is available in open access under Creative Common Attribution-Non-Commercial-No Derivatives 4.0 International (CC BY-NC-ND 4.0) license, which allows downloading and sharing articles with others as long as they credit the authors and the publisher, but without permission to change them in any way or use them commercially. For commercial use, please contact the journal office at kardiologiapolska@ptkardio.pl.
