Treatment of Heavily Calcified Unprotected Left Main Disease With Lithotripsy: The First Case Series

Abstract: We present the first case series using Shockwave Intravascular Lithotripsy (S-IVL; Shockwave Medical), a novel coronary calcium modification device, in patients with heavily calcified unprotected left main (LM) coronary artery disease (CAD). Decisions regarding surgical vs percutaneous revascularization in LM-CAD patients are based on anatomical complexity and perceived surgical risk. In this series, we present the use of S-IVL in a patient with LM-CAD with multivessel disease who declined surgery, a patient with an isolated LM-CAD and severe cardiomyopathy, and a late nonagenarian patient where surgical revascularization was not an option.

J INVASIVE CARDIOL 2019;31(6):E143-E147.

Key words: calcification, complications, high-risk PCI

Left main (LM) coronary artery disease (CAD) carries higher prognostic risk compared with other subsets of ischemic heart disease, due to the large myocardial territory involved.¹ Management of LM-CAD has traditionally been with coronary artery bypass grafting (CABG), but percutaneous coronary intervention (PCI) is increasingly becoming a viable option with the advancement in technology and use of drug-eluting stent (DES) implantation. Recent evidence that has compared CABG vs PCI using DES in patients with LM-CAD suggests comparable clinical outcomes.^2,3 Current guidelines suggest PCI as a class IA recommendation in patients with LM-CAD with low Synergy between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score ≤22, and an alternative (class IIa) to CABG for patients with intermediate anatomical complexity (SYNTAX score, 23-32).⁴ Heavily calcified LM-CAD increases procedural complexity, and makes PCI less favorable. Upfront calcium modification with rotational or orbital atherectomy in calcified unprotected LM-CAD has been shown in observational studies with good procedural success rates.⁵ However, rotational and orbital atherectomy carry the risk of potential complications such as microembolization or perforation, which could be fatal in LM-CAD.

Shockwave Intravascular Lithotripsy

Shockwave Intravascular Lithotripsy (S-IVL; Shockwave Medical, Inc) is a novel device that was granted the European CE mark in May 2017 for use in heavily calcified coronary artery lesions prior to stent implantation. It uses sonic waves at the target site to deliver pulsatile lithotripsy, which selectively fractures intimal and medial layer calcium. S-IVL balloons are available in 2.5-4.0 mm diameters and are 12 mm in length; the balloons are connected to a generator capable of delivering up to 8 cycles of lithotripsy (10 pulses per cycle). We have previously described its ease of use and success in a “real-world” patient cohort.⁶ To our knowledge, we were the first to describe the use of S-IVL in an unprotected ostial LM stem (LMS) in a patient whose surgical risk was too high.⁷ With increasing experience with the S-IVL device, we have continued to utilize the S-IVL device in patients with unprotected LM-CAD with success. The first case series is described herein.

Case #1

A 60-year-old woman presented with non-ST elevation myocardial infarction (NSTEMI) and underwent coronary angiography, which revealed a calcified moderate stenosis in the LMS extending into a severe ostial left anterior descending (LAD) coronary artery stenosis (Figure 1A; Video 1). The right coronary artery (RCA) had a chronic total occlusion (CTO) of the mid vessel (Figure 1B) and the proximal left circumflex (LCX) artery was moderately stenosed (fractional flow reserve obtained with an Abbott Vascular pressure wire was 0.9). There was an additional bifurcation lesion at the mid LAD and second diagonal artery (Figure 1C). Although the anatomical complexity was high (SYNTAX score, 35), and despite adequate counseling, the patient declined to undergo CABG, so multivessel PCI was planned. Due to an extremely small-caliber right radial artery, this was done via a right femoral approach. Following engagement of the RCA with a 6 Fr Amplatz left (AL) 1 guide catheter, antegrade CTO-PCI was successful with two DESs deployed in the RCA (Figure 2A). The LMS was engaged with an Extra-Backup XB 3.5 guide catheter (Cordis). Attempts were made to predilate the LMS and proximal LAD using various compliant and non-compliant balloons, but luminal gain remained unsatisfactory. We then elected to use a 3.0 x 12 mm S-IVL balloon to deliver 8 cycles of lithotripsy to the calcific lesion (Figure 2B). Without further predilation/lesion preparation, a 3.5 x 38 mm Synergy DES (Boston Scientific) was advanced and deployed at the LMS-LAD and postdilated with good result (Figure 2C). This was then overlapped with a 2.5 x 18 mm Xience Alpine DES (Abbott Vascular) and a 2.25 x 12 mm Synergy DES in the mid LAD (Figure 2D). A good angiographic result was achieved, with minimal residual stenosis and Thrombolysis in Myocardial Infarction (TIMI) 3 flow (Figures 2E and 2F; Video 2).

Case #2

A 64-year-old man without cardiac history presented with dyspnea on exertion, orthopnea, and pitting edema; he was found to have severe cardiomyopathy on transthoracic echocardiography with a left ventricular ejection fraction of 25%-30%. He underwent a coronary angiogram, which revealed severe calcific stenosis of the distal LMS and proximal LAD (Figure 3A; Video 3), with mild disease elsewhere (SYNTAX score, 15). He was felt to be a high operative risk, and after appropriate discussion he underwent PCI. Using a 6 Fr transradial system, the LMS was engaged with a 6 Fr XB 3.5 guide catheter. The calcific lesion in the LMS and proximal LAD was initially predilated with a 2.5 mm non-compliant balloon. This allowed a 3.5 x 12 mm S-IVL balloon to be inflated at the target site and 8 cycles of lithotripsy were delivered (Figure 3B). Without further predilation, a 3.5 x 38 mm Synergy DES was deployed at the target site (Figure 3C) and postdilated with non-compliant balloons. Angiographic success was achieved without complications with minimal residual stenosis (Figure 3D; Video 4). No circulatory support was required for the procedure.

Case #3

An independent 96-year-old male presented with ongoing chest pain, elevated cardiac biomarkers, and dynamic electrocardiographic changes; he was managed as a high-risk NSTEMI and underwent urgent coronary angiography. This revealed moderate stenosis of the proximal RCA, first diagonal, and obtuse marginal arteries. The culprit lesion was a severe calcified distal LM and proximal LAD stenosis with TIMI 2 flow (Figures 4A and 4B; Video 5). His SYNTAX score was 32, and the decision was made to perform PCI on the LMS/proximal LAD only. Using a 6 Fr transradial approach, the LMS was engaged with an XB 3 guide catheter and coronary guidewires were passed into the distal LAD and LCX arteries. The LMS and proximal LAD were initially predilated with compliant and non-compliant balloons. A 4.0 x 12 mm S-IVL balloon was then used and 6 cycles of lithotripsy were delivered to the LMS/proximal LAD (Figure 4C). A 4.0 x 28 mm Synergy DES was then deployed and postdilated with a 5.0 x 12 mm non-compliant balloon (Figure 4D). There was good final angiographic result with mild pinching of the LCX ostium, but preserved TIMI 3 flow (Figures 4E and 4F; Video 6).

Discussion

In this first case series of S-IVL use in unprotected LM-CAD patients, we have shown the device to be a useful tool to assist interventional cardiologists in complex PCI cases. It can be used both as an upfront technique after initial predilation with compliant or non-compliant balloons to deliver immediate calcium modification, or as a bailout if the luminal gain with balloon angioplasty is inadequate to facilitate stent delivery. In our case series, we have utilized the S-IVL device in multiple scenarios, including LM-CAD with associated three-vessel disease in a patient who declined CABG, in a patient with isolated LMS-proximal LAD disease, and in a very elderly patient where surgical revascularization was not an option.

No patients had procedural complications or major adverse events (stroke, myocardial infraction, death) during the index admission or within the first 30 days post discharge.

The SYNTAX score was designed to predict adverse outcomes based on anatomical complexities in patients with LM-CAD and/or multivessel disease.⁸ One of the characteristics that increase anatomical complexity is the presence of heavy calcification, which adds 2 points to the score per each significant lesion that is heavily calcified. Heavy coronary calcification was present in 49% of patients in the PCI group of the SYNTAX trial,⁹ wherein calcium modification devices were not systematically utilized. Although there is no current evidence comparing S-IVL with balloon angioplasty prior to stent placement, its use in LM-CAD or multivessel disease that is complicated by heavy calcification may make PCI more favorable or tenable.

Study limitations. This is a small, single-center case series demonstrating the use of S-IVL in patients with heavily calcified, unprotected LM-CAD. Although we achieved angiographic success without complications in all patients, this series does not allow us to draw conclusions regarding the safety or long-term outcomes of using the device in LM-CAD.

Conclusion

Heavy calcification of coronary stenoses, particularly in the setting of LM-CAD or multivessel disease, can make PCI complex and unfavorable. The use of S-IVL in these cases may simplify lesion preparation and optimize procedural outcomes.

References

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View the Supplemental Video here.

From the Department of Cardiology, North Shore Hospital, Auckland, New Zealand.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

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

Manuscript submitted April 8, 2019, accepted April 15, 2019.

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