Prior aspirin use predicts worse outcomes in patients with non-ST-elevation acute coronary syndromes. PURSUIT Investigators. Platelet IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy.

Aspirin is beneficial in the prevention and treatment of cardiovascular events, but patients who have events while taking aspirin may have worse outcomes than those not on aspirin. We investigated the association between prior aspirin use and clinical outcomes in 9,461 patients with non-ST-elevation acute coronary syndromes enrolled in the Platelet IIb/IIIa in Unstable angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) trial, before and after adjustment for baseline factors. We also examined whether eptifibatide has a differential treatment effect in prior aspirin users. Prior aspirin users were less likely to have an enrollment myocardial infarction (MI) (vs unstable angina) (43.9% vs 48.8%, p = 0.001) but more likely to have death or MI at 30 days (16.1% vs 13.0%, p = 0.001) and at 6 months (19.9% vs 15.9%, p = 0.001). After adjustment, prior aspirin users remained less likely to have an enrollment MI (odds ratio 0.88, 95% confidence interval 0.79 to 0.97) and more likely to have death or MI at 30 days (odds ratio 1.16, 95% confidence interval 1.00 to 1.33) but not at 6 months (odds ratio 1.14, 95% confidence interval 0.98 to 1.33). In a multivariable model, eptifibatide did not have a different treatment effect in prior aspirin users compared with nonusers (p = 0.534). Prior aspirin users had fewer enrollment MIs but worse long-term outcomes than nonusers. We found no evidence for a different treatment effect of eptifibatide in prior aspirin users.