Six-Month versus Twelve-Month Dual Antiplatelet Therapy after Implantation of Drug-Eluting Stents

Background —The optimal duration of dual antiplatelet therapy (DAPT) after implantation of drug-eluting coronary stents (DES) remains undetermined. We aimed to test whether 6-month DAPT would be noninferior to 12-month DAPT after implantation of DES. Methods and Results —We randomly assigned 1443 patients undergoing implantation of DES to receive 6-month or 12-month DAPT (in a 1:1 ratio). The primary end point was a target vessel failure (TVF) defined as the composite of cardiac death, myocardial infarction, or ischemia-driven target vessel revascularization at 12 months. Rates of TVF at 12 months were 4.8% in the 6-month DAPT group and 4.3%  in the 12-month DAPT group (the upper limit of one-sided 95% confidence interval [CI], 2.4%; P =0.001 for noninferiority with a pre-defined noninferiority margin of 4.0%). Although stent thrombosis tended to occur more frequently in the 6-month DAPT group than in 12-month one (0.9% versus 0.1%; hazard ratio 6.02, 95% CI 0.72-49.96; P =0.10), the risk of death or myocardial infarction did not differ in the 2 groups (2.4% versus 1.9%; hazard ratio 1.21, 95% CI 0.60-2.47; P=0.58). In the prespecified subgroup analysis, TVF occurred more frequently in the 6-month DAPT group than in the 12-month one (hazard ratio 3.16; 95% CI 1.42-7.03; P=0.005) among diabetic patients. Conclusions —Six-month DAPT did not increase the risk of TVF at 12 months after implantation of DES compared with 12-month DAPT. However, noninferiority margin was wide, and the study was underpowered for death or myocardial infarction. Our results need to be confirmed in larger trials.