Background  After percutaneous coronary intervention (PCI) for non–ST-segment elevation myocardial infarction (NSTEMI), treatment with a P2Y12 antagonist with aspirin is recommended for 1 year.

Objectives  The oral P2Y12 antagonists ticagrelor and prasugrel have higher recommendations than clopidogrel, but it is unknown if administration before the start of PCI is beneficial.

Methods  In the randomized, double-blind ACCOAST (A Comparison of prasugrel at the time of percutaneous Coronary intervention Or as pre-treatment At the time of diagnosis in patients with non–ST-segment elevation myocardial infarction) trial, 4,033 patients were diagnosed with NSTEMI and 68.7% underwent PCI; 1,394 received pre-treatment with prasugrel (30-mg loading dose), and 1,376 received placebo. At the time of PCI, patients who received pre-treatment with prasugrel received an additional 30-mg dose of prasugrel, and those who received placebo received a 60-mg loading dose of prasugrel. Primary efficacy was a composite of cardiovascular death, myocardial infarction, stroke, urgent revascularization, or glycoprotein IIb/IIIa bailout through 7 days from randomization. Investigators captured the presence of thrombus on initial angiography and during PCI.

Results  The incidence of the primary endpoint through 7 days from randomization in the pre-treatment group versus the no pre-treatment group was 13.1% versus 13.1% (p = 0.93). Pre-treatment with prasugrel was not associated with decreases in any ischemic event, including total mortality. Patients with thrombus on angiography had a 3-fold higher incidence of the primary endpoint than patients without thrombus. There was no impact of pre-treatment with prasugrel on the presence of thrombus before PCI or on occurrence of stent thrombosis after PCI. There was a 3-fold increase in all non–coronary artery bypass graft Thrombolysis In Myocardial Infarction (TIMI) major bleeding and a 6-fold increase in non–coronary artery bypass graft life-threatening bleeding with pre-treatment with prasugrel; the same trends persisted in patients who had radial or femoral access even with use of a closure device.

Conclusions  These findings support deferring treatment with prasugrel until a decision is made about revascularization in patients with NSTEMI undergoing angiography within 48 h of admission. (A Comparison of prasugrel at the time of percutaneous Coronary intervention Or as pre-treatment At the time of diagnosis in patients with non—ST-segment elevation myocardial infarction [ACCOAST]; NCT01015287)