Calcified Coronary Lesions Treated With Intravascular Lithotripsy: One-Year Outcomes

We previously described the first real-world series of PCI involving Shockwave intravascular lithotripsy (S-IVL), including use in acute coronary syndromes and left main interventions. In this follow-up, we report the 1-year outcomes of patients treated with S-IVL during their PCI. 

J INVASIVE CARDIOL 2020;32(7):E200-E201.

Key words: clinical outcomes, Shockwave lithotripsy

Calcified lesions often increase the complexity of percutaneous coronary intervention (PCI) and risk of future adverse events. Shockwave intravascular lithotripsy (S-IVL; Shockwave Medical) has been shown to be an effective calcium-modification tool in preparing calcified coronary lesions prior to stent placement. Its circumferential, pulsatile soundwaves provide a different mechanism to fracture calcium compared with existing devices such as rotational atherectomy and cutting balloons. Although short-term safety outcomes have been positive, longer-term outcomes have yet to be reported. We previously described the first real-world series of PCI involving S-IVL, including use in acute coronary syndromes and left main interventions.^1-3 We report the 1-year outcomes of patients treated with S-IVL during their PCI. 

Consecutive patients treated with S-IVL at our center between October 2018 and April 2019 were included. All target lesions had at least moderate calcification angiographically and PCI was performed in a standard manner via a 6 Fr transradial system, as previously described.¹ We assessed cardiovascular mortality, recurrent myocardial infarction (MI), and ischemia-driven target-lesion revascularization (TLR) at 1-year follow-up. Categorical variables are presented as absolute numbers and population percentages. Descriptive summaries of continuous variables are presented as mean ± standard deviation.

During this period, a total of 44 patients were treated with S-IVL during their PCI at our center. The mean age was 70.8 ± 8.0 years and 24 (54.5%) were men. Indications for PCI were: acute coronary syndromes in 25 patients (56.8%), stable angina in 17 patients (38.6%), ischemic cardiomyopathy in 1 patient (92.3%), and PCI before transcatheter aortic valve implantation in 1 patient (2.3%). None of the patients had procedural complications or in-hospital adverse outcomes. All patients achieved successful stent delivery and angiographic success with <20% residual stenosis. 

There was 1 cardiovascular death at day 10 after PCI, related to a patient with atrial fibrillation who suffered a hemorrhagic stroke while on triple-antithrombotic therapy. Additionally, there were 3 non-cardiovascular deaths at 1 year (2 malignancies and 1 aspiration pneumonia). Three patients experienced a non-ST segment elevation MI and required repeat intervention; TLR was undertaken for early in-stent restenosis in 2 of the 3 patients, while the third patient had intervention of a non-IVL target lesion. 

The first in-stent restenosis occurred on day 62 in a 66-year-old man with end-stage kidney disease on hemodialysis. During the index procedure, he was found to have an in-stent restenosis of a drug-eluting stent in a calcified proximal left anterior descending coronary artery implanted 6 months prior. He was treated with 8 cycles of lithotripsy using a 4.0 x 12 mm S-IVL balloon within the previous stent. This was followed by a drug-coated balloon without further stent placement. Given the recurrent restenosis, he required further PCI and stenting. The second restenosis occurred on day 242 in an 84-year-old female. During her index procedure, a diffusely diseased right coronary artery was treated with 8 cycles of lithotripsy using a 3.5 x 12 mm S-IVL balloon, followed by 2 overlapping drug-eluting stents (3.0 x 48 mm and 3.5 x 18 mm Xience Xpedition; Abbott Vascular). On the repeat coronary angiogram, a stent fracture and severe restenosis were identified within the 3.0 x 48 mm drug-eluting stent, at the bifurcation of the right marginal branch (Figure 1). This area of restenosis was treated with a 3.5 x 12 mm Synergy drug-eluting stent (Boston Scientific).

S-IVL has been a unique innovation in preparing calcified coronary lesions with several key advantages. First, S-IVL has an over-the-wire balloon-based system that requires minimal additional training for interventional cardiologists. Second, in our experience, S-IVL can avoid some of the complications associated with atherectomy, such as distal embolization and guidewire bias. Third, the circumferential supersonic waves delivered by S-IVL are able to fracture both superficial and deeper calcium layers while having minimal effect on normal vascular tissue. 

There are several important limitations of the current iteration of S-IVL, the Shockwave C2 catheter system, that operators need to consider when performing PCI on calcified coronary lesions. The delivery profile of 0.043˝ to 0.046˝ remains bulky, and often requires reasonable predilation with compliant or semicompliant balloons in order to deliver the S-IVL balloon to the target lesion. The widely reported electrical capture or “Shocktopics” during lithotripsy cycles are not well understood, but are more common in patients with a resting heart rate of <65 beats/min.⁴ Although there have been no reported ventricular arrhythmias associated with this phenomenon, we have previously reported cases of electromechanical coupling⁵ and de novo atrial fibrillation following S-IVL use.⁶

In conclusion, S-IVL has been a user-friendly and safe device that has helped operators achieve procedural success for calcified coronary lesions. To our knowledge, these are the first reported 1-year outcomes following S-IVL use and the rates of adverse events are low. As our experience with S-IVL grows and future iterations of the system are developed, ongoing research is required to improve clinical outcomes in PCI of calcified coronary lesions.

From the North Shore Hospital, Auckland, New Zealand.

Disclosure: The authors have completed and returned the ICMJE Form for Dis- closure of Potential Conflicts of Interest. The authors report no conflicts of in- terest regarding the content herein.

The authors report that patient consent was provided for publication of the images used herein.

Manuscript accepted May 2, 2020.

Address for correspondence: Bernard Wong, MBChB, North Shore Hospital, 124 Shakespeare Rd, Takapuna, Auckland 0620, New Zealand. Email: bernardwong@ hotmail.co.nz

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