Contemporary Antiplatelet Therapy and Clinical Outcomes of Japanese Patients With Acute Myocardial Infarction ― Results From the Prospective Japan Acute Myocardial Infarction Registry (JAMIR) ―

BACKGROUND: Antiplatelet therapy is the corner stone of treatment following acute myocardial infarction (AMI). Prasugrel, a new and potent antiplatelet agent, was recently introduced to clinical practice. We compared the clinical outcomes of patients with AMI treated with prasugrel with those treated with clopidogrel in real-world clinical practice in Japan. METHODS AND RESULTS: The Japan AMI Registry (JAMIR) is a multicenter, nationwide, prospective registry enrolling patients with AMI from 50 institutes. Between December 2015 and May 2017, a total of 3,411 patients were enrolled. Among them, 3,069 patients were treated with either prasugrel (n=2,607) or clopidogrel (n=462) during hospitalization. Median follow-up period was 12 months. Prasugrel-treated patients were predominantly male, younger, more often showed ST-elevation AMI, and had fewer comorbidities. After adjustment using inverse probability of treatment weighting, the primary endpoint, defined as a composite of cardiovascular death, non-fatal MI and non-fatal stroke, was comparable between the prasugrel and clopidogrel groups (adjusted hazard ratio [HR] 1.07, 95% confidence interval [CI] 0.67-1.72), whereas the risk of major bleeding (BARC type 3 or 5 bleeding) was significantly lower in the prasugrel group (adjusted HR 0.62, 95% CI 0.39-0.99). CONCLUSIONS: The present real-world database of the JAMIR demonstrated that the potent P2Y12-inhibitor prasugrel showed comparable rates of 1-year ischemic events to clopidogrel, but the risk of bleeding was lower with prasugrel than with clopidogrel.