Stent Thrombosis, Clinical Events, and Influence of Prolonged Clopidogrel Use After Placement of Drug-Eluting Stent. Data From an Observational Cohort Study of Drug-Eluting Versus Bare-Metal Stents

Objectives: The purpose of this study was to evaluate the risk of stent thrombosis (ST), clinical outcomes, and the benefits of extended clopidogrel use after drug-eluting stent (DES) implantation. Background: Data are limited regarding uniform evaluation of ST and the influence of clopidogrel continuation beyond 12 months on late events after DES treatment. Methods: We identified 7,221 patients who received DES implantation (n = 3,160) or bare-metal stent (BMS) implantation (n = 4,061), and compared long-term adverse outcomes. Additionally, 2,851 patients with DES surviving 12 months without major events were analyzed according to clopidogrel continuation. Results: The adjusted-risk of overall ST was similar in the 2 groups. After 1 year, however, DES patients showed a higher risk of ST; definite/probable (hazard ratio [HR]: 3.55, 95% confidence interval [CI]: 1.26 to 9.99). The adjusted-risk of death (HR: 0.60, 95% CI: 0.46 to 0.79), death/myocardial infarction (HR: 0.63, 95% CI: 0.49 to 0.81), and target lesion revascularization (HR: 0.32, 95% CI: 0.24 to 0.43) were significantly lower in the DES group than in the BMS group. Continuing clopidogrel beyond 12 months was not associated with a reduced risk for ST (HR: 0.54, 95% CI: 0.07 to 4.23), death (HR: 1.20, 95% CI: 0.55 to 2.66), or death/myocardial infarction (HR: 1.16, 95% CI: 0.56 to 2.42) after DES implantation. Conclusions: As compared with BMS, DES showed a similar risk of overall ST, but a higher risk of very late ST. The rates of death, death/myocardial infarction, and target lesion revasuclarization were significantly lower in the DES group. Clopidogrel continuation beyond 1 year did not appear to reduce ST and clinical events after DES implantation.