Coronary Stent Thrombosis in Acute Coronary Syndromes

Background: In ACS patients who are treated with a primary percutaneous coronary intervention (pPCI), stent thrombosis is a serious and potentially lethal complication. We analysed the occurrence, risk factors and outcomes of angiographically proven (definite) stent thrombosis in patients with ACS undergoing pPCI enrolled in the prospective multicentre Swiss Special Programme University Medicine (SPUM-ACS) registry. Methods: The prospectively gathered data of consecutive patients with ACS, who were enrolled from December 2009 to October 2012, were analysed at 1 year regarding the primary outcome of definite stent thrombosis. An independent committee reviewed all the events. Baseline data of 2131 patients were considered for analysis. 2004 patients underwent pPCI, and 1843 had coronary stenting; of these, 1473 (79.9%) received a drug-eluting stent (DES), 338 (18.3%) a bare metal stent (BMS) and 30 (1.6%) both stent types. Results: 20 of the 1843 patients (1.1%) had developed definite stent thrombosis at 1 year. Of the DESs that thrombosed, one was first-generation (sirolimus), 7 second-generation (5 everolimus, 2 zotarolimus) and 3 third-generation (biolimus). 7 thrombosed stents were BMS, and in 2 cases the affected stent type could not be determined. 11 DESs and 7 BMSs (0.7% and 2.1%, respectively) developed thrombosis (p = 0.03). There were 14 cases of early (<30 days) and 6 cases of late (30 days to 1 year) stent thrombosis. On average, early stent thromboses occurred 5.7 days and late ones 259.7 days after pPCI. Significant risk factors for stent thrombosis were female gender, presentation as a STEMI and anteroseptal infarction on ECG (p = 0.03, 0.01 and 0.02, respectively). Surprisingly, patients on clopidogrel prior to pPCI were also at higher risk for stent thrombosis (p = 0.048). Angiographically proven restenosis of a pre-existing stent, occlusion or thrombus at the site of stenting, insertion of more than two stents and residual stenosis distal to the implanted stent were further significant risk factors (p = 0.03, 0.01, 0.03, 0.048 and 0.03, respectively). Patients with stent thrombosis had a higher mortality rate than patients without thrombosis (15% compared to 3.7%; p = 0.01). Conclusion: With current stent technology and guideline-based ACS management, stent thrombosis is rare, albeit associated with high mortality. (Study registered at ClinicalTrials.gov, no. NCT01000701.)