Shockwave Intravascular Lithotripsy of Calcified Coronary Lesions in ST-Elevation Myocardial Infarction: First-in-Man Experience

Abstract: We present the first cases of Shockwave intravascular lithotripsy (S-IVL; Shockwave Medical), a novel coronary calcium modification device, being used in patients undergoing percutaneous coronary intervention for ST-elevation myocardial infarction (STEMI). The 3 presented cases include an upfront use of S-IVL in a right coronary artery, an in-stent restenosis, and a community cardiac arrest/STEMI equivalent where S-IVL was used as a bail-out technique to facilitate stent delivery in a tortuous calcified vessel.

J INVASIVE CARDIOL 2019;31(5):E73-E75.

Key words: calcified lesions, lithotripsy, STEMI

Balloon angioplasty in calcified coronary lesions can be challenging and is associated with suboptimal stent expansion and apposition. Aggressive balloon predilation in eccentric calcified lesions may increase the risk of edge dissection of the non-calcified vessel wall, with insufficient luminal gain and minimal calcium modification.¹

Shockwave intravascular lithotripsy (S-IVL; Shockwave Medical) is a novel calcium modification device used in heavily calcified coronary lesions prior to stent delivery. The Disrupt-CAD (Disrupt Coronary Artery Disease) trial has shown S-IVL to be safe in stable and unstable angina,² while we have previously shown our experience of its use in all-comers with heavily calcified lesions requiring percutaneous coronary intervention (PCI).³

The Shockwave IVL Device

The S-IVL device is a single-use, monorail catheter with a central ultrasound core delivered over a 0.014˝ angioplasty wire. It contains lithotripsy emitters that are encased in an integrated balloon. Balloons range from 2.5 to 4.0 mm in diameter and are all 12 mm in length. Low-pressure inflation (4 atm) ensures apposition to the vessel wall and is maintained throughout the time of Shockwave delivery. Each lithotripsy cycle is 10 seconds at a frequency of 1 pulse/second. Each catheter is capable of performing 8 cycles of lithotripsy. A minimum of two cycles of lithotripsy is recommended at each area of concern and may overlap.

Sonic pressure waves are generated when the emitters vaporize the fluid inside the S-IVL balloon, causing a rapidly expanding and collapsing bubble. This acoustic energy selectively fractures the intimal and medial calcium layers of the lesion, which increases vessel compliance and optimizes stent expansion.

Case #1

A 76-year-old man presenting with acute chest pain with inferior ST-elevation on electrocardiogram (ECG) was found to have severe, diffuse calcific disease in the right coronary artery (RCA) with Thrombolysis in Myocardial Infarction (TIMI) 2 flow (Figure 1A; Video 1). Following engagement using a transradial 6 Fr Amplatz Left (AL) 0.75 guide catheter, a Balance guidewire (Abbott Vascular) was passed into the posterior descending artery (PDA). A 3.0 x 12 mm S-IVL balloon was used, with 8 cycles of lithotripsy delivered throughout the calcific RCA (Figure 1B).

Two overlapping 3.0 x 48 mm Xience Xpedition (Abbott Vascular) drug eluting stents (DESs) were then delivered to the RCA (Figure 1C). Following postdilation with a non-compliant balloon, there was minimal residual stenosis and TIMI 3 flow was achieved (Figure 1D; Video 2). Severe disease in the left coronary arteries was treated via a staged PCI procedure.

Case #2

A 70-year-old man presented with acute-onset chest pain with associated inferior ST-elevation on ECG. Medical history was significant for inferior STEMI 11 years prior, which was thrombolyzed and treated percutaneously with a DES to the mid-RCA. Coronary angiogram revealed mild disease in his left coronary system and a calcific occlusion of his mid-RCA stent (Figure 2A; Video 3). Using a transradial 6 Fr Judkins Right (JR) 4 guide catheter, a Balance MiddleWeight guidewire (Abbott Vascular) was passed into the posterolateral branch of the RCA. Following predilation of the mid-RCA with compliant balloons, a Sion Blue buddy wire (Asahi Intecc) was passed into the PDA. A 3.5 x 48 mm Synergy DES (Boston Scientific) could not pass the proximal RCA due to tortuosity and calcification on multiple attempts despite further predilation with a 3.5 mm non-compliant balloon and GuideLiner (Teleflex) support (Figure 2B). The JR 4 guide catheter was switched to an AL 1 for extra guide support. A 4.0 x 12 mm S-IVL balloon was then passed and 8 cycles of lithotripsy were delivered to the proximal and mid-RCA (Figure 2C). The GuideLiner was then used to facilitate delivery of a 3.0 x 12 mm Resolute Onyx DES (Medtronic), which was overlapped with a 4.0 x 48 mm Synergy DES in the proximal RCA (Figures 2D and 2E). There was minimal residual stenosis following postdilation and TIMI 3 flow was achieved (Figure 2F; Video 4).

Case #3

A 61-year-old man was transferred from a peripheral hospital following a community cardiac arrest, preceded by 30 minutes of chest pain. He was noted to be in complete heart block on admission with a new left bundle-branch block on ECG. He was intubated and required stabilization with vasopressors and transvenous pacing via a temporary wire. Coronary angiogram revealed a heavily calcified, subtotal proximal occlusion of a large obtuse marginal (OM) artery (Figure 3A; Video 5). A transradial Extra-Backup 3.5 guide catheter (Cordis) was engaged and a Balance MiddleWeight guidewire was passed to the distal OM. The DES was unable to be passed even with buddy wire support, due to tortuosity and calcification of the vessel. A 3.0 x 12 mm S-IVL balloon was then used and 5 cycles of lithotripsy were delivered to the lesion (Figure 3B). A 3.0 x 24 mm Synergy DES was then easily delivered and deployed in the OM artery (Figure 3C). Although the procedure was complicated by ventricular tachycardia requiring 6 shocks, good final angiographic result with TIMI 3 flow was achieved (Figure 3D; Video 6).

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Discussion

PCI in patients with STEMI can be complicated by the presence of calcified coronary plaques. We have previously shown S-IVL to be a safe device to use for coronary calcium modification that does not require much additional training for interventional cardiologists.³ To our knowledge, these are the first documented cases in man on the use of S-IVL in primary PCI for STEMI cases. In this case series, we have demonstrated the S-IVL device can be easily utilized in conjunction with various PCI tools/techniques such as GuideLiners and buddy wires, in order to facilitate optimal stent delivery. Although there is no current evidence to support the use of S-IVL in PCI for STEMI, our early experience with its adjunct use has been favorable.

Study limitations. This is a small, single-center case series, which does not allow any conclusions on safety, efficacy, and outcome benefit of S-IVL in PCI for STEMI patients. Further studies are needed to investigate the long-term benefits of Shockwave use in order to broaden the applicability of the device.

Conclusion

When PCI for STEMI is complicated by the presence of heavy calcification, the S-IVL technique appears to be a safe and straightforward option to help achieve procedural success.

References

1. Mehanna E, Abbott JD, Bezerra HG. Optimizing percutaneous coronary intervention in calcified lesions: insights from optical coherence tomography of atherectomy. Circ Cardiovasc Interv. 2018;11:e006813.

2. Brinton TJ, Ali ZA, Hill JM, et al. Feasibility of Shockwave coronary intravascular lithotripsy for the treatment of calcified coronary stenoses. Circulation. 2019;139:834-836.

3. Wong B, El-Jack S, Newcombe R, Glenie T, Armstrong G, Khan A. Shockwave intravascular lithotripsy for calcified coronary lesions: first real-world experience. J Invasive Cardiol. 2019;31:46-48.

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.

Manuscript submitted March 15, 2019 and accepted March 20, 2019.

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