Efficacy and Safety of Adjusted-Dose Prasugrel Compared With Clopidogrel in Japanese Patients With Acute Coronary Syndrome

Background: Prasugrel is an antiplatelet agent that shows more prompt, potent, and consistent platelet inhibition than clopidogrel. The objective of this study was to confirm the efficacy and safety of prasugrel at loading/maintenance doses of 20/3.75mg. Methods and Results: Japanese patients (n=1,363) with acute coronary syndrome undergoing percutaneous coronary intervention were randomized to either prasugrel (20/3.75mg) or clopidogrel (300/75mg), both in combination with aspirin (81–330mg for the first dose and 81–100mg/day thereafter), for 24–48 weeks. The primary efficacy endpoint was the incidence of major adverse cardiovascular events (MACE) at 24 weeks, defined as a composite of cardiovascular death, nonfatal myocardial infarction, and nonfatal ischemic stroke. We compared the incidence of MACE between the 2 groups using point estimates. Safety outcomes included the incidence of bleeding events until 2 weeks after the last dose. The incidence of MACE at 24 weeks was 9.4% in the prasugrel group and 11.8% in the clopidogrel group (risk reduction 23%, hazard ratio 0.77, 95% confidence interval 0.56–1.07). The incidence of non-coronary artery bypass graft-related major bleeding was similar in both groups (1.9% vs. 2.2%). Conclusions: Prasugrel 20/3.75mg was associated with a low incidence of ischemic events, similar to the results of TRITON-TIMI 38, and with a low risk of clinically serious bleeding in Japanese ACS patients. (Circ J 2014; 78: 1684–1692)