AimsThe TRA·CER trial compared vorapaxar, a novel platelet protease-activated receptor (PAR)-1 antagonist, with placebo in 12 944 patients with high-risk non-ST-segment elevation acute coronary syndromes (NSTE ACS). In this analysis, we explored the effect of vorapaxar on myocardial infarction (MI).Methods and resultsA blinded, independent central endpoint adjudication committee prospectively defined and classified MI according to the universal MI definition, including peak cardiac marker value (creatine kinase-MB [CK-MB] and/or troponin). Because the trial failed to meet its primary endpoint, these analyses are considered exploratory. During a median follow-up of 502 days, 1580 MIs occurred in 1319 patients. The majority (n = 1025, 64.9%) were type 1 (spontaneous) MI, followed by type 4a [percutaneous coronary intervention (PCI)-related] MI (n = 352; 22.3%). Compared with placebo, vorapaxar reduced the hazard of a first MI of any type by 12% [hazard ratio (HR), 0.88; 95% confidence interval (CI), 0.79-0.98; P = 0.021] and the hazard of total number of MIs (first and subsequent) by 14% (HR, 0.86; 95% CI, 0.77-0.97; P = 0.014), an effect that was sustained over time. Vorapaxar reduced type 1 MI by 17% (HR, 0.83; 95% CI, 0.73-0.95; P = 0.007). Type 4a MIs were not significantly reduced by vorapaxar (HR, 0.90; 95% CI, 0.73-1.12; P = 0.35). Vorapaxar effect was consistent across MI sizes defined by peak cardiac marker elevations and across key clinical subgroups; however, in patients not treated with thienopyridine at baseline (HR, 0.65; 95% CI, 0.46-0.92) compared with patients who received thienopyridine (HR, 0.91; 95% CI, 0.81-1.02), there was a trend towards a higher effect (Pint = 0.077).ConclusionThe PAR-1 antagonist vorapaxar was associated with a reduction of MI, including total number of infarctions. This reduction was sustained over time and was mostly evident in type 1 MI, the most common type of MI observed.