Intravascular lithotripsy for optimized percutaneous coronary intervention of a 30-year-old saphenous vein graft: a case report

Abstract

Background

Intravascular lithotripsy (IVL) is approved for native coronary calcium modification, but data in saphenous vein grafts (SVGs) are scarce.

Case summary

An 87-year-old man with remote coronary artery bypass grafting presented with chest pain and was found to have non–ST-elevation myocardial infarction and new left ventricular dysfunction. Angiography revealed severe multi-vessel disease, with an 80% proximal lesion in a 30-year-old SVG collateralizing multiple territories with new wall motion abnormality. Percutaneous coronary intervention with embolic protection was attempted, but dense circumferential calcification limited balloon expansion. IVL with a 2.5 mm Shockwave balloon delivering 120 pulses allowed intravascular ultrasound passage, successful stent deployment, and satisfactory expansion.

Discussion

This case demonstrates successful off-label IVL use in SVG percutaneous coronary intervention, adding to limited reports and highlighting its potential in challenging revascularization.

Learning points.

• Severely calcified saphenous vein graft lesions and their increased prevalence in an ageing population represent an ongoing challenge in complex coronary revascularization.

• Intravascular lithotripsy can facilitate optimal stent deployment in situations beyond native coronary arteries, warranting further study.

Introduction

Intravascular lithotripsy (IVL) has emerged as an effective modality to tackle coronary artery calcification¹ to facilitate optimal stent expansion during percutaneous coronary intervention (PCI). Its use has been mostly defined in arterial (coronary and peripheral) calcification,¹ allowing low-pressure balloon dilation and enhancing vessel compliance.¹ In this case report, we aim to demonstrate the safe use of IVL for the PCI of an old, calcified saphenous vein graft (SVG).

Summary figure

Case presentation

An 87-year-old male presented with severe heartburn-like discomfort that had been progressively worsening over the prior two weeks and was particularly persistent for the preceding 24 h. There was no radiation of the sensation, and no associated shortness of breath, nausea, or vomiting. Over-the-counter medications provided no relief, prompting his visit to the emergency department. On presentation, initial vital signs were within normal limits. Physical exam was significant only for epigastric tenderness without rebound or guarding.

Past medical history included essential hypertension, dyslipidaemia, type 2 diabetes mellitus, bilateral coronary artery stenosis, severe peripheral arterial disease, chronic kidney disease, moderate aortic stenosis, gastrointestinal reflux disease, lumbar radiculopathy, and multi-vessel coronary artery disease with a non-ST elevation myocardial infarction (NSTEMI) in 1994 status post two-vessel coronary artery bypass grafting (CABG) and left ventricular (LV) aneurysmectomy. Bypass grafts included a left internal mammary artery to the left anterior descending artery (LAD) (known to be occluded) and a reverse SVG to the right posterior descending artery (RPDA).

Initial electrocardiogram demonstrated normal sinus rhythm with Q waves in the anterior leads (Figure 1). Complete blood count, metabolic panel, and liver function were within normal limits except for a creatinine level of 1.8 mg/dl (baseline 1.4). High-sensitivity troponin T was elevated to 1300 ng/l. He was initiated on a heparin drip for presumed NSTEMI.

Figure 1.

Admission electrocardiogram showing normal sinus rhythm with Q waves in the anterior leads.

Transthoracic echocardiogram showed new LV systolic dysfunction with an ejection fraction of 44%. There were regional wall motion abnormalities in the distal LAD territory, as well as low-flow, low-gradient severe aortic stenosis. Valve area was calculated to be 0.8 cm², with peak transaortic velocity of 2.8 m/s and a mean gradient of 20 mmHg.

Diagnostic coronary angiography showed severe distal left main disease extending into the circumflex, chronic total occlusion of the mid LAD and the ostial right coronary artery (RCA) (see Video S1A, S1B), and an 80% proximal lesion in the SVG to RPDA. The SVG was also seen to give collaterals to the distal LAD and circumflex territories (see Video S2). Right heart catheterization showed low filling pressures bilaterally, mild pulmonary hypertension, and normal cardiac output of 4.6 l/min and index of 2.6 l/min/m².

Given significant disease and calcification, and because the patient had been chest pain free for the preceding 12 h, no ad hoc PCI was performed. The structural heart team was consulted, and a multidisciplinary meeting was held to decide on a revascularization plan. Because the SVG to the RCA was perfusing not only the RPDA territory but also the LAD and circumflex territories, we decided to proceed with SVG PCI (rather than PCI of the native RCA chronic thrombotic occlusion), followed by outpatient transcatheter aortic valve replacement.

PCI of the SVG was performed using the Filterwire EZ embolic protection system (Boston Scientific, Marlborough, MA, USA). After initial pre-dilation, an intravascular ultrasound (IVUS) catheter was introduced but would not traverse the lesion, which was seen to have dense 360° calcification proximally (Figure 2). Despite serial pre-dilation with 2.5 mm semi-compliant and noncompliant balloons, there was a persistent ‘waist’ in the lesion, suggesting inadequate expansion (Figure 3). Therefore, a 2.5 mm Shockwave C2 IVL balloon was used to administer a total of 120 pulses with balloon inflations at 4 atmospheres each. Subsequent angiography demonstrated noticeable improvement in luminal diameter throughout the treated segment (see Video S3).

Figure 2.

Intravascular ultrasound of the proximal edge of lesion showing 360° calcification.

Figure 3.

Persistent ‘waist’ seen in lesion during balloon pre-dilation (arrow).

The IVUS catheter was successfully advanced past the lesion. The lesion was heavily calcified with evidence of cracks and luminal gain after IVL. A 3.0 × 20 mm Synergy XD drug-eluting stent was deployed across the lesion. The stent was post-dilated using a 3.0 mm noncompliant balloon to high pressures. Final angiography demonstrated adequate stent expansion with 30% residual waist (see Video S4), which was pragmatically accepted rather than attempting further dilation or IVL.

The Filterwire system was successful in preventing distal embolization of a sizable chunk of calcium that had likely dislodged during IVL (Figure 4).

Figure 4.

Calcium caught in embolic protection system (arrow).

Our patient was discharged on dual antiplatelet therapy 48 hours after his PCI and started on guideline-directed medical therapy as an outpatient. Six weeks after his discharge, he underwent elective valve replacement with no complications. Echocardiogram performed six weeks after revealed an ejection fraction of 40%–45%. He remains asymptomatic >90 days post-PCI and has returned to his baseline level of activity.

Discussion

With an ageing population and improving survival, neo-calcification in decades-old vein graft lesions has emerged as a growing challenge. Older patients are often at prohibitive risk for redo CABG due to mediastinal scarring, absence of suitable revascularization targets, and advanced comorbidities.² PCI is therefore preferred, with native vessels generally favoured for superior long-term outcomes.² However, in select cases, such as ours, SVG PCI remains the best or only feasible option. IVL is recognized in ESC guidelines as an option for calcium modification in native coronary arteries³; however, its use in SVGs is not addressed and remains limited to case reports/series.^4–7

The primary concerns in SVG PCI lie in the durability of the stent placed, the risk of distal embolization of friable atheromatous debris, and the resultant slow flow/no-reflow phenomenon, which has been associated with increased peri-procedural myocardial infarction and mortality.⁸ As demonstrated, the use of an embolic protection system proved beneficial in our case in preventing the embolization of sizeable calcium debris. Additionally, since the durability of SVG stents are limited,^9,10 it is vital to approach each case individually, weighing patient age, life expectancy, stent durability, and the associated morbidity and mortality risk of the procedure against the consequences of not intervening.

Our case demonstrates the successful off-label use of IVL to facilitate PCI of a heavily calcified SVG, adding one more weapon to our arsenal for complex percutaneous revascularization. IVL presents a promising option for modifying calcified vein graft lesions, warranting further investigation to evaluate its safety, efficacy, and long-term impact in SVG PCI.

Conclusion

Off-label use of IVL enabled safe and effective PCI of a severely calcified SVG, supporting its role as an additional tool in complex revascularization.

No new data were generated or analysed in support of this research.

Lead author biography

Ashwin Kumar, MBBS, is a PGY-3 Internal Medicine resident at the University of Connecticut in the United States. He completed his medical school in Bangalore, India, where he developed an early interest in academic medicine. He has been elected as a chief medical resident and plans to pursue a fellowship in cardiovascular diseases in the future.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports online.

Author contributions

Ashwin Kumar (Methodology, Validation, Visualization [equal], Writing—review & editing [equal], Writing—original draft [lead]), Vinyas Shraffi Venkatesh (Validation, Writing—review & editing [equal], Writing—original draft [supporting]), and Boskey Patel (Conceptualization, Investigation [lead], Methodology, Supervision, Validation, Visualization [equal], Writing—review & editing [equal])

Consent: Consent for submission and publication of this case report including images and associated text has been obtained from the patient in line with COPE guidance.

Funding

None declared.