Clopidogrel Versus Aspirin as an Antiplatelet Monotherapy After 12-Month Dual-Antiplatelet Therapy in the Era of Drug-Eluting Stents

Background— The use of dual-antiplatelet therapy (DAPT) exceeding 12 months may increase a bleeding risk despite a lower risk of ischemic events. There is no study to compare clinical outcomes in patients treated with a single-antiplatelet drug after DAPT in the era of drug-eluting stents (DES). We sought to investigate the efficacy and safety of clopidogrel versus aspirin monotherapy after 12-month DAPT after DES implantation using an institutional registry. Methods and Results— This observational study was conducted on consecutive patients receiving DES between January 2003 and December 2010. A total of 3243 patients receiving 12-month DAPT after DES implantation without adverse clinical outcomes were divided into 2 groups based on prescribed antiplatelet status: aspirin (n=2472) and clopidogrel (n=771). Clinical, angiographic, and procedural characteristics revealed more comorbidities and more complex lesions in the clopidogrel group than in the aspirin group. At 36 months after initiation of antiplatelet monotherapy, clopidogrel was associated with a reduction in risk for a composite of cardiac death, myocardial infarction, or stroke (aspirin versus clopidogrel; 3.8% versus 2.6%; hazard ratio, 0.54; 95% confidence interval, 0.32–0.92; P =0.02). The risk of cardiac death was lower with clopidogrel monotherapy than with aspirin monotherapy (1.4% versus 0.5%; hazard ratio, 0.31; 95% confidence interval, 0.11–0.93; P =0.04). Thrombolysis in myocardial infarction major bleeding occurred similarly between both groups (0.9% versus 1.3%; hazard ratio, 1.03; 95% confidence interval, 0.46–2.32; P =0.95). Conclusions— After 12-month DAPT, clopidogrel monotherapy, when compared with aspirin monotherapy, might be associated with a reduced risk of recurrent ischemic events in patients receiving DES.