Temporal Variations in Ischemic and Bleeding Event Risks after Acute Coronary Syndrome during Dual Antiplatelet Therapy

Background This study estimates the temporal risk variations of ischemic and bleeding events during dual antiplatelet therapy (DAPT) and suggests the optimal period for DAPT after acute coronary syndrome (ACS) categorized by the Academic Research Consortium for High Bleeding Risk (ARC-HBR) criteria. Methods A total of 1,264 ACS patients receiving either clopidogrel or prasugrel with aspirin were classified by ARC-HBR criteria into HBR (n = 574) and non-HBR groups (n = 690). This study was designed as a multicenter observation to evaluate the primary endpoints of ischemic, including cardiogenic death, myocardial infarction, or ischemic stroke, and bleeding events, defined as Bleeding Academic Research Consortium type 3 or 5. The temporal risk variations were estimated using the Cox hazard and Royston-Parmar models. Results Ischemic and bleeding events were observed in 9.4% and 7.4% of patients, respectively, during an average observation period of 313 days. The HBR group had a higher incidence of both events than the non-HBR group (15.3% vs. 4.5%, P < 0.01 for ischemic; 11.9% vs. 3.8%, P < 0.01 for bleeding). The estimated risk curves revealed a peak and steep decline in the first few days, followed by a constant decline. The peak of risk was higher for bleeding than for ischemic events, but this relationship reversed early, with ischemic events displaying a higher risk in both the HBR and non-HBR groups until at least 60 days. Conclusion A 60-day period of DAPT is appropriate to balance the risks of adverse events after ACS, regardless of ARC-HBR criteria.