Aspirin Omission at the Time of Primary Percutaneous Coronary Intervention in STEMI

The safety of omitting up-front treatment with aspirin during primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) remains unclear.

We conducted a multicenter, open-label, randomized trial in Japan involving patients with STEMI who were undergoing primary PCI. Patients were randomly assigned in a 1:1 ratio before PCI to receive low-dose prasugrel monotherapy or dual antiplatelet therapy (DAPT) with aspirin and low-dose prasugrel for 12 months. The primary outcome was a composite of death from any cause, stroke, or myocardial infarction at 12 months, which was assessed for noninferiority with a prespecified noninferiority margin of 1.50 for the 95% confidence interval of the hazard ratio. The major secondary outcome was major bleeding (defined as a bleeding event of Bleeding Academic Research Consortium [BARC] type 3 [nonfatal major bleeding] or 5 [fatal bleeding]) at 12 months, which was assessed for superiority if noninferiority was established for the primary outcome.

A total of 2216 patients were included in the full analysis population; 1109 were assigned to receive monotherapy and 1107 to receive DAPT. At 12 months, death from any cause, stroke, or myocardial infarction had occurred in 124 patients (Kaplan-Meier estimate, 11.0%) in the monotherapy group and in 94 patients (Kaplan-Meier estimate, 8.5%) in the DAPT group (hazard ratio, 1.34; 95% confidence interval [CI], 1.02 to 1.75; P = 0.40 for noninferiority). Major bleeding had occurred in 61 patients (Kaplan-Meier estimate, 5.6%) in the monotherapy group and in 92 patients (Kaplan-Meier estimate, 8.4%) in the DAPT group (hazard ratio, 0.66; 95% CI, 0.47 to 0.91). The percentages of patients with definite or probable stent thrombosis and serious adverse events appeared to be similar in the two groups.

Among patients with STEMI who were undergoing primary PCI, low-dose prasugrel monotherapy initiated before PCI was not noninferior to DAPT for 12 months with respect to a composite of death from any cause, stroke, or myocardial infarction at 12 months. (Funded by Boston Scientific Japan; PREMIUM ClinicalTrials.gov number, NCT05709626.).