Prior aspirin users with acute non-ST-elevation coronary syndromes are at increased risk of cardiac events and benefit from enoxaparin

Background The aim of this article was to investigate whether prior aspirin use in patients with acute coronary syndromes affects clinical outcome. Th e Efficacy Safety Subcutaneous Enoxaparin in Non-Q-Wave Coronary Events Stu dy (ESSENCE) and Thrombolysis in Myocardial Infarction (TIMI) 11B trials ha ve shown superiority of enoxaparin over unfractionated heparin (UFH) in pat ients with unstable angina and non-ST-segment elevation myocardial infarcti on (UA/NSTEMI). However, the treatment effect of enoxaparin in the subset o f patients reporting prior aspirin use has not been determined. Methods The rate of death, myocardial infarction, and urgent revascularizat ion at days 8 and 43 after randomization was compared among patients who re ceived aspirin within the week before randomization with those who did not receive aspirin in the TIMI 11B trial. A total of 3275 patients (84%) were prior aspirin users. Results The admission diagnosis was similar for prior and nonprior aspirin users. At both day 8 and day 43 the event rate was higher for prior aspirin users than for nonprior aspirin users (odds ratio 1.6 [1.24-2.08], P = .00 04 at day 43), even after correction for baseline characteristics. Compared with those prior aspirin users taking UFH, enoxaparin-treated prior aspiri n users had a reduced rate of the composite end point of death, myocardial infarction, and urgent revascularization at day 8 (odds ratio 0.82 [0.67-1. 00], P = .046) and day 43 (odds ratio 0.83 [0.70-0.98], P = .032). Conclusion Patients with UA/NSTEMI and prior aspirin use had a 60% higher r isk of death and cardiac ischemic events compared with nonprior aspirin use rs. On the basis of this subanalysis, enoxaparin is superior to UFH in all patients. In prior aspirin users the benefit is more clearly demonstrated.