Very Late Stent Thrombosis after Sirolimus-Eluting Stent Implantation Observed Using Optical Coherence Tomography and Coronary Angioscopy

Sirolimus-eluting stents (SES) are now commonly used for percutaneous coronary intervention (PCI) because they dramatically reduce the rates of restenosis and target lesion revascularization, even in small vessels and long lesions as compared with bare-metal stent.¹ The unresolved issue about SES use is the possibility of late stent thrombosis. Late stent thrombosis is a very rare, but serious complication that may result in acute myocardial infarction or sudden cardiac death.² However, the mechanism of late stent thrombosis with SES has not been established. We report a patient with very late stent thrombosis 37 months after SES implantation who underwent optical coherence tomography and coronary angioscopy.

Very Late Stent Thrombosis after Sirolimus-Eluting Stent Implantation Observed Using Optical Coherence Tomography and Coronary Angioscopy

ABSTRACT: Sirolimus-eluting stents (SES) are now commonly used for percutaneous coronary intervention (PCI) because they dramatically reduce the rates of restenosis and target lesion revascularization, even in small vessels and long lesions as compared with bare-metal stent.¹ The unresolved issue about SES use is the possibility of late stent thrombosis. Late stent thrombosis is a very rare, but serious complication that may result in acute myocardial infarction or sudden cardiac death.² However, the mechanism of late stent thrombosis with SES has not been established. We report a patient with very late stent thrombosis 37 months after SES implantation who underwent optical coherence tomography and coronary angioscopy. J INVASIVE CARDIOL 2010;22:557–558 ————————————————————

Case Report

A 61-year-old male presented with acute coronary syndrome manifested by chest pain and ST-segment elevation in leads II, III and aVF. He had a previous history of coronary angioplasty for stable angina pectoris. In June 2005, two sirolimus-eluting stents (SES) (Cypher, Cordis Corp., Miami Lakes, Florida) had been implanted at the proximal right coronary artery (RCA). One proximal stent was 3.0 × 13 mm and the other was 2.5 × 28 mm, which was overlapped. Six months after SES implantation, coronary angiography showed no restenosis. Aspirin (100 mg/day) with a low dose of ticlopidine (100 mg/day) was prescribed thereafter. He was free from angina until the current episode. Thirty-seven months later, he felt chest pain when he returned home after working in the garden for 2 hours on a hot summer day of July 2009. The symptoms were resistant to sublingual nitroglycerin, and an ambulance was called. When the patient was admitted to our hospital, his chest pain continued and electrocardiography showed transient ST-segment elevation in leads II, III and aVF. Emergency coronary angiography revealed perfusion delay with thrombus-like shadow at the proximal RCA where a 2.5 × 28 mm SES had been implanted previously. Thrombectomy was performed using an aspiration catheter and thrombolysis in myocardial infarction (TIMI) flow grade 3 was obtained 110 minutes after the onset of chest pain. Then, we performed optical coherence tomography (OCT) and coronary angioscopy. OCT showed neointimal coverage over the stent struts at the distal portion of the 2.5 × 28 mm SES. At the mid-to-proximal portion of the stent, a large thrombus was observed over the stent struts, which were not covered by neointima. Some of the stent struts were malapposed. The minimum stent diameter was 2.22 mm (stent area, 4.20 mm²), suggesting stent underexpansion. Angioscopy revealed yellow-colored plaque under uncovered stent struts, with adhering mixed thrombus. The lesion was dilated using a 3.0 × 15 mm Powered Lacrosse balloon catheter (Goodman Co. Ltd., Aichi, Japan) at 26 atm. The final TIMI flow grade 3 with a minimum stent diameter of 3.07 mm (stent area, 7.44 mm²) were achieved (Figures 1 and 2). The patient fully recovered without a significant increase in creatine kinase and was discharged 3 days later. Drug-eluting stents (DES) have significantly reduced the rate of restenosis and the need for repeat revascularizations compared with bare-metal stents (BMS).¹ However, despite a reduction in restenosis and revascularization rates, DES do not ensure long-term safety because there is the risk of late stent thrombosis, which may occur more than 1 year after DES implantation.³ The mechanism of late stent thrombosis seems to be multifactorial, and several factors have been reported to be associated with the occurrence of late stent thrombosis. In this case, undersizing of the coronary stent, longer stent length, incomplete neointimal coverage over the stent, malapposition and the presence of yellow plaque were observed by OCT and coronary angioscopy. A higher incidence of stent malapposition at follow up was reported in SES than in BMS in the RAVEL trial. It was reported that 2.2% of SES struts were malapposed at 6-month follow up by OCT, and the predictors of SES malapposition were chronic total occlusion (CTO) and overlapped stents.⁴ The mechanism for the increased malapposition in a CTO lesion may be positive vessel remodeling or the absorption of thrombi with suppressed neointimal hyperplasia. As for overlapping SES segments, excessive inhibition of neointimal hyperplasia due to the doubled dose of sirolimus may be a factor. In this case, 2 SES were implanted and overlapped. In addition, dehydration and increased sympathetic activity might have triggered stent thrombosis. We think that late stent thrombosis is not a common complication under appropriate antiplatelet therapy, but caution must be exercised to correctly deploy and expand stents in this DES era.

References

1. Morice MC, Serruys PW, Sousa JE, et al. A randomized comparison of a sirolimus-eluting stent with a standard stent for coronary revascularization: Randomized study with the sirolimus-coated Bx Velocity balloon-expandable stent in the treatment of patients with de novo native coronary lesions. N Engl J Med 2002;346:1773–1780 2. Cutlip DE, Baim DS, Ho KK, et al. Stent thrombosis in the modern era: A pooled analysis of multicenter coronary stent trial. Circulation 2001;103:1967–1971. 3. Kastrati A, Mehilli J, Pache J, et al. Analysis of 14 trials comparing sirolimus-eluting stents with bare-metal stent. N Engl J Med 2007;356:1030–1039. 4. Matsumoto D, Shite J, Shinke T, et al. Neointimal coverage of sirolimus-sluting stents at 6-month follow-up: Evaluated by optical coherence tomography. Eur Heart J 2007;28:961–967.

———————————————————— From the Department of Cardiology, Hiroshima City Hospital, Hiroshima, Japan. The authors report no conflicts of interest regarding the content herein. Manuscript submitted February 24, 2010, provisional acceptance given March 29, 2010, final version accepted May 3, 2010. Address for correspondence: Masaharu Ishihara, MD, PhD, FACC, Department of Cardiology, Hiroshima City Hospital, 7-33, Moto-machi, Naka-ku, Hiroshima, 730-8518 Japan. E-mail: ishifami@fb3.so-net.ne.jp