Effects of Prolonged Dual Antiplatelet Therapy in ST-Segment Elevation vs. Non-ST-Segment Elevation Myocardial Infarction

Background: The benefits and risks of prolonged dual antiplatelet therapy (DAPT) have not been studied extensively across a broad spectrum of acute coronary syndromes. In this study we investigated whether treatment effects of prolonged DAPT were consistent in patients presenting with ST-segment elevation myocardial infarction (STEMI) vs. non-STEMI (NSTEMI). Methods and Results: As a post hoc analysis of the SMART-DATE trial, effects of >= 12 vs. 6 months DAPT were compared among 1,023 patients presenting with STEMI and 853 NSTEMI patients. The primary outcome was a composite of recurrent myocardial infarction (MI) or stent thrombosis at 18 months after the index procedure. Compared with the 6-month DAPT group, the rate of the composite endpoint was significantly lower in the >= 12-month DAPT group (1.2% vs. 3.8%; hazard ratio [HR] 0.31, 95% confidence interval [CI] 0.12-0.77; P=0.012). The treatment effect of >= 12- vs. 6-month DAPT on the composite endpoint was consistent among NSTEMI patients (0.2% vs. 1.2%, respectively; HR 0.20, 95% CI 0.02-1.70; P=0.140; P-interaction=0.718). In addition, >= 12-month DAPT increased Bleeding Academic Research Consortium (BARC) Type 2-5 bleeding among both STEMI (4.4% vs. 2.0%; HR 2.18, 95% CI 1.03-4.60; P=0.041) and NSTEMI (5.1% vs. 2.2%; HR 2.37, 95% CI 1.08-5.17; P=0.031; P-interaction=0.885) patients. Conclusions: Compared with 6-month DAPT, >= 12-month DAPT reduced recurrent MI or stent thrombosis regardless of the type of MI at presentation.