Background--The manifestations, complications, and outcomes of cardiovascular disease differ between women and men. The safety and efficacy of pharmacological reperfusion therapy in women with ST-elevation myocardial infarction are of particular interest.

Methods and Results--We investigated outcomes in the Enoxaparin and Thrombolysis Reperfusion for Acute Myocardial Infarction Treatment-Thrombolysis in Myocardial Infarction (ExTRACT-TIMI) 25 study, which randomized ST-elevation myocardial infarction patients with planned fibrinolysis to enoxaparin or unfractionated heparin. Compared with men (n=15 696), women (n=4783) were older and more likely to have hypertension and diabetes (P<0.001). The unadjusted 30-day mortality rate for women was >2-fold higher than for men (13.2% versus 5.4%; odds ratio, 2.66; 95% CI, 2.40 to 2.96). After adjustment for age, fibrinolytic therapy, revascularization, region, and elements of the TIMI Risk Score, women had a 1.25-fold-higher 30-day risk of death (95% CI, 1.08 to 1.46) but similar risk of intracerebral hemorrhage (adjusted odds ratio, 0.81; 95% CI, 0.52 to 1.26). The 30-day rate of death or nonfatal MI in women was reduced by enoxaparin compared with unfractionated heparin in women (15.4% versus 18.3%; P=0.007). Major bleeding was more frequent in women receiving enoxaparin compared with those receiving unfractionated heparin (2.3% versus 1.4%; P=0.022) but similar among women and men receiving enoxaparin (2.3% versus 2.0%; P=0.39). The rates of death, nonfatal myocardial infarction, or nonfatal major bleeding (net clinical benefit) were lower with enoxaparin (absolute risk reduction, 2.6% in women [P=0.02] and 1.6% in men [P=0.001]).

Conclusions--In ExTRACT-TIMI 25, women presented with a profile of higher baseline risk and increased short-term mortality. In this large, contemporary clinical trial, women had similar relative and greater absolute risk reductions than men when treated with enoxaparin compared with unfractionated heparin as adjunctive therapy with fibrinolysis.