Late-Acquired Stent Malapposition after Sirolimus-Eluting Stent Implantation (Full title below)

Late-Acquired Stent Malapposition after Sirolimus-Eluting Stent Implantation following Acute Coronary Syndrome: Angiographic, IVUS, OCT and Coronary Angioscopic Observation

ABSTRACT: Drug-eluting stents (DES) have been shown to significantly reduce the incidence of restenosis and target lesion revascularization in a wide variety of clinical situations. DES have also been shown to significantly reduce neointimal hyperplasia as compared to bare-metal stents. However, the antiproliferative properties of DES also delay vascular healing and have been associated with stent malapposition, hypersensitivity reactions and late stent thrombosis. Stent thrombosis could result in myocardial infarction or death. We describe here a case report of late stent malapposition following sirolimus-eluting stent implantation observed by angiography, intravascular ultrasound, optical coherence tomography and angioscopy. J INVASIVE CARDIOL 2009;21:666–667 Case Presentation. A 39-year-old male underwent stent implantation (Cypher™ 3.5–33 mm, Cordis Corp., Miami Lakes, Florida) for acute coronary syndrome in a proximal left anterior descending (LAD) artery lesion. Coronary angiography (Figure 1A) and intravascular ultrasound (IVUS) (Figure 2A) images post procedure show a well apposed stent to the vessel wall, with a good result. Follow-up routine coronary angiography performed at 18 months after stenting showed contrast staining outside the stent margin suggestive of incomplete stent apposition (ISA) (Figure 1B). The patient subsequently underwent IVUS assessment, optical coherence tomography (OCT), and coronary angioscopy (CAS). IVUS (Figure 2B) shows ISA, as there is a clear separation seen between stent struts and vessel wall, with an overall dilated vessel compared to the post-procedure IVUS. OCT (Figures 3A, 3B) images showed malapposed stent struts, peristrut ulcerations, poor endothelialization of the stent struts, fibrin and microthrombi. CAS images (Figure 4A–4D) revealed some exposed stent struts, visible stent struts and red thrombi in between the stent struts. This case demonstrates late-acquired stent malapposition following sirolimus-eluting stent implantation for the treatment of acute coronary syndrome. Late-acquired stent malapposition has been associated with the occurrence of late stent thrombosis following DES implantation.1 As shown in our case, the ISA may have been associated with poor endothelialization of the stent struts and exposure of the stent struts to the blood stream, which provides a nidus for thrombus formation, as shown in this patient. This phenomenon is due to several reported factors: delayed vascular healing of the vessel, positive arterial remodeling and dissolution of the thrombus between the stent and the vessel wall.2,3 Long-term antiplatelet therapy seems logical in these cases, but is still debated. Further studies are needed, therefore, to clarify the association between ISA and late stent thrombosis. From *The Cardiothoracic Centre, Liverpool, United Kingdom, and §Toyohashi Heart Center, Toyohashi, Japan. Manuscript submitted June 19, 2009, provisional acceptance given July 13, 2009, final version accepted September 14, 2009. Address for correspondence: Sudhir Rathore, MBBS, MD, MRCP(UK), The Cardiothoracic Centre, Department of Cardiology, Thomas Drive, Liverpool, L14 3PE. United Kingdom. E-mail: sudhirrathore@hotmail.com

1. Cook S, Wenaweser P, Togni M, et al. Incomplete stent apposition and very late stent thrombosis after drug-eluting stent implantation. Circulation 2007;115:2426–2434.

2. Mintz GS, Shah VM, Weissman NJ. Regional remodelling as the cause of late stent malapposition. Circulation 2003;107:2660–2663.

3. van der Hoeven BL, Liem SS, Jukema W, et al. Sirolimus eluting stents versus bare metal stents in patients with ST- segment elevation myocardial infarction: 9-month angiographic and intravascular ultrasound results and 12-month clinical outcome. Results from the MISSION! Intervention study. J Am Coll Cardiol 2008; 51:718–726.