Prolonged Dual Antiplatelet Therapy After Stent Implantation: What Are the Risks and Benefits?

Whether to continue dual antiplatelet therapy (DAPT) for more than 12 months after drug-eluting stent (DES) implantation is controversial. In this international, industry-funded, randomized, placebo-controlled trial, 9961 DES recipients who received DAPT for 1 year were assigned to aspirin plus a thienopyridine or placebo for an additional 18 months. Only patients without a major event or significant bleeding in the first year after stenting were eligible for randomization.

Between 12 and 30 months, the incidence of definite or probable stent thrombosis was significantly lower in the DAPT group than in the placebo group (0.4% vs. 1.4%; hazard ratio, 0.29) as was the incidence of major adverse cardiovascular and cerebrovascular events (4.3% vs. 5.9; HR, 0.71). The rate of myocardial infarction was reduced by approximately 50% with prolonged DAPT (2.1% vs. 4.1%; HR, 0.47; P<0.001), even in patients without stent thrombosis (HR, 0.59; P<0.001). An increased rate of moderate or severe bleeding (by the GUSTO criteria) with DAPT (2.5% vs. 1.6%; HR, 1.61; 95% P=0.001) was attributable mainly to patients with moderate, not severe, bleeding; fatal bleeding did not differ between the two groups. Cardiovascular mortality was similar in the two groups, and an increase in all-cause mortality in the DAPT group was nonsignificant after adjustment for cancer diagnosed before enrollment. A subgroup analysis suggested greater ischemic benefit of prolonged DAPT with paclitaxel-eluting stents (HR, 0.52) than with everolimus-eluting stents (HR, 0.89; P=0.05 for interaction).