Very late stent expansion with intracoronary lithotripsy: a case report.

BACKGROUND: Underexpanded stent in heavily calcified coronary lesion is common and persists over years. It is related to long-term failure and negative outcomes. Treatment of this situation after many years with intracoronary lithotripsy (ICL-Shockwave®) could be an option. CASE
SUMMARY: We report a case of a man with underexpanded coronary stent implanted 11 years earlier. Optical coherence tomography highlighted the mechanism of stent underexpansion showing the presence of calcium stones under the old struts. Intracoronary lithotripsy crushed calcium under the stent struts causing its geometric change (from elliptical to round shape) and a consequent better transmission of the true radial force of the old stent. DISCUSSION: Heavily calcified coronary lesions lead to stent underexpansion which persists over years. Intracoronary lithotripsy could be a very late option to manage this unfavourable common result.

Percutaneous treatment of calcified coronary lesions requires dedicated devices.

Intracoronary lithotripsy could be an option to correct underexpanded stents.

Intravascular imaging is very useful in-stent failure. New technologies like optical coherence tomography co-registration are crucial to detect site and mechanisms of failure.

The crushing of calcium under stent struts permits transmission of the true radial force of stent implanted many years earlier.

Introduction

Treatment of heavily calcified coronary lesions remains challenging. For many years, the strategies to manage these situations have been cutting and scoring balloons, high pressure balloons and rotational atherectomy., Also post-dilatation with non-compliant balloons could fail. The resulting underexpanded stent is related to long-term failure and negative outcomes. Intracoronary lithotripsy (ICL-Shockwave®) is a new option for these issues. Intracoronary lithotripsy has been designed for preparation of calcified lesions, but its use after the stent implantation remains uncertain. We report a case of a patient admitted at our department after positive stress test. Coronary angiography showed severe in-stent restenosis on ostial left anterior descending (LAD) and development of severe atherosclerosis in the intermediate portion of native vessel. Optical coherence tomography (OCT-Abbott®) highlighted struts underexpansion in the middle of the old stent. Intracoronary lithotripsy caused calcium micro-fractures under the stent struts with final good expansion.

Case presentation

An 83-year-old male with hypertension, dyslipidaemia, former smoker was admitted at our division after a positive stress test. Eleven years before, he underwent drug-eluting stent implantation in ostial-proximal LAD [sirolimus-eluting stent (SES) 3.5/28 mm)] for angina symptoms. The cardiovascular and respiratory examinations on admission were normal. Blood pressure was 130/80 mmHg, electrocardiogram showed regular heart rate of 65 b.p.m. First-line blood test was normal. His medical therapy on admission was: aspirin 100 mg/day, ramipril 2.5 mg/day, bisoprolol 1.25 mg/day, and simvastatin 20 mg/day. Coronary angiography showed severe ostial in-stent restenosis and atherosclerotic progression in mid-LAD (, Supplementary material online, Video S). By 6-Fr radial approach, two SESs (SES 2.75/12 mm + SES 3.0/28 mm) were implanted in mid-distal portion of LAD overlapping the distal portion of the old stent. The OCT was subsequently performed confirming the good apposition of new stents and the severe in-stent neo-atherosclerosis in ostial LAD (). Real-time co-registration highlighted diffuse calcifications under the central portion of the old stent struts that have led to underexpansion [minimal lumen area (MLA) 4.1 mm2, , Supplementary material online, Video S]. Multiple prolonged inflations in underexpanded site with non-compliant balloon were performed (3.5/20 mm + 3.5/12 mm at 28 atm for 30 s). Hourglass images persisted during all inflations. Therefore, four cycles of 10 impulses of ICL were performed (4.0/12 mm balloon inflated at 6 atm). Better expansion of non-compliant balloons was obtained. Provisional stenting in left main bifurcation with one-stent crossover into LAD (SES 4.0/18 mm) was followed by non-compliant balloon post-dilatations (4.0/15 mm + 5.0/12 mm). Final OCT scan showed the crushed calcium under the old struts (, Supplementary material online, Video S3) confirming the good angiographic result (MLA 6.81 mm2, , Supplementary material online, Video S4). Geometric change of the old stent, from elliptical to a round shape, was highlighted by OCT analysis (). No major complications during the procedure or hospitalization occurred. Dual antiplatelet therapy with clopidogrel and aspirin was prescribed for 6 months. At 1 year of follow-up, the patient was free of angina and on good clinical status.

(A) Basal angiogram. Sub-occlusive stenosis in the mid part of left anterior descending and severe in-stent restenosis on ostial left anterior descending (asterisks). Full arrow points underexpanded struts of the old stent (dashed line). (B) Pre-lithotripsy optical coherence tomography scan (frame position is pointed by full arrow in A). Elliptical-shape underexpanded stent (MLA 4.1 mm2) with calcium stones under the struts (asterisks).

(A) Post-lithotripsy optical coherence tomography scan (frame position is pointed by full arrow in B). Round-shape expansion of the old stent (MLA 6.81 mm2) with crushed calcium under the struts (asterisks). (B) Final angiogram. New stents (continuous lines) partially overlapped with the old stent (dashed line).

(A) Basal calcium distribution and stent size. (B) Crushed calcium and geometric change after lithotripsy.

Discussion

Percutaneous treatment of calcified coronary lesions is challenging. Evidences suggest an optimal lesion preparation before stent implantation. This has been obtained for many years with cutting and scoring balloons or rotational atherectomy., Underutilization of these techniques has led to the current evidence of underexpanded stents.

Anecdotal reports propose the treatment of these situations with atherectomy of the stent., Intracoronary lithotripsy is a new technique based on calcium rupture by ultrasound waves. Recent reports support the use of ICL as bail-out therapy for underexpanded stents.,

Although little is known about the effect of ICL on stents implanted recently, even less is known about its utilization on stents implanted many years earlier.

Intravascular imaging is very useful in these situations. New technologies like OCT co-registration are crucial to detect the site and the mechanisms of stent failure.

In our case, the OCT permitted to describe the mechanism of stent underexpansion showing the presence of calcium stones under the old struts. Intravascular measurements were useful to predict the deliverability and balloon size of ICL device.

Its recommended to maintain 1:1 ratio between ICL balloon and vessel diameter. Reassured by the presence of old supportive struts, we decided to perform ICL with a higher ratio (ICL balloon of 4.0 mm in a vessel medium diameter of 3.5 mm, 1.15:1 ratio).

Intracoronary lithotripsy acted in-stent underexpanded part causing its geometric change (from elliptical to round shape) and a consequent better transmission of the true radial force of stent implanted 11 years before.

The circumferential stent expansion significantly improved after ICL (stent symmetry index: pre 0.67 vs. post 0.91).

Conclusion

Percutaneous treatment of heavily calcified coronary lesions remains challenging. Late failure due to stent underexpansion and malapposition is common. Intravascular imaging is crucial to detect the site and the mechanisms of the stent failure. Intracoronary lithotripsy in underexpanded stents implanted many years before is safe and effective. Intracoronary lithotripsy is able to crush calcium stone under the stent struts. Interventional cardiologists should keep in mind this new device and approach to manage complex coronary interventions.

Lead author biography

Andrea Demarchi, MD, was born in 1986 in Italy. He completed his School of Medicine at University of Pavia in 2011. He started his activity as interventional cardiologist in 2015. Specialized in Cardiology at University of Pavia on 2017 with a thesis ‘Acute Coronary Syndrome in patients with previous CABG: treatment and long term prognosis’. His professional training in interventional cardiology passed through University of Pavia, Legnano and Crema Hospital, Polyclinic of Monza. At present, he is a MD at Cardiology in S. Andrea Hospital, Vercelli.

Supplementary material

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

Slide sets: A fully edited slide set detailing this case and suitable for local presentation is available online as Supplementary data.

Consent: The author/s confirm that written consent for submission and publication of this case report including image(s) and associated text has been obtained from the patient in line with COPE guidelines.

Conflict of interest: none declared.

Click here for additional data file.

2008	Drug-eluting stent implantation on proximal left anterior descending for angina
2019	Underexpansion of the old stent and development of atherosclerosis Optical tomography coherence confirms under expansion and its mechanism Intracoronary lithotripsy inside the old stent is performed causing its geometric change and a consequent better transmission of the true radial force