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.

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