Impact of reduced-dose prasugrel vs. standard-dose clopidogrel on in-hospital outcomes of percutaneous coronary intervention in 62 737 patients with acute coronary syndromes: a nationwide registry study in Japan

Aims In Japan, reduced-dose prasugrel (loading/maintenance dose, 20/3.75mg) has been approved for use in acute coronary syndrome (ACS) patients undergoing percutaneous coronary intervention (PCI), because of the higher bleeding risk among East Asians. However, its safety in the real-world population has not been investigated. We aimed to evaluate the effectiveness and safety of reduced-dose prasugrel vs. standard-dose clopidogrel in ACS patients undergoing PCI. Methods and results Acute coronary syndrome patients who underwent PCI in 2016, who were treated with either reduced-dose prasugrel or standard-dose clopidogrel in addition to aspirin, were identified from the nationwide Japanese PCI registry. The primary outcome was in-hospital mortality following PCI. Secondary outcomes included stent thrombosis and bleeding complication after PCI. Among 62 737 ACS patients who underwent PCI at any of 986 participating centres across Japan (clopidogrel 31.9%; prasugrel 68.1%), we identified 12 016 propensity score-matched pairs (24 032 patients; age 69.412.2years; female 24.9%; ST-elevation myocardial infarction 42.3%). Compared with standard-dose clopidogrel, reduced-dose prasugrel was associated with increased risk of bleeding [odds ratio (OR) 1.65, 95% confidence interval (CI) 1.10-2.51; P=0.016], but both had similar rates of mortality (OR 1.11, 95% CI 0.89-1.38; P=0.371) and stent thrombosis (OR 1.29, 95% CI 0.73-2.30; P=0.387) as well as similar falsification endpoints of cardiac tamponade and emergent operation. Conclusion In Japanese ACS patients undergoing PCI, the risk of bleeding is higher when using reduced-dose prasugrel than when using standard-dose clopidogrel, but there is no significant difference in in-hospital mortality and incidence of stent thrombosis between the two antiplatelet regimens.