Enoxaparin for 7 days was better than unfractionated heparin for 2 days for reducing death and MI but not bleeding in STEMI.

M e t h o d s Design: Randomized controlled trial (The Enoxaparin and Thrombolysis Reperfusion for Acute MI Treatment−Thrombolysis in MI [ExTRACT-TIMI] 25 study). Allocation: Concealed.* Blinding: Blinded (clinicians, patients, {data collectors, outcome assessors, and manuscript writers}†.* Follow-up period: 30 days. Setting: 674 centers in 48 countries. Patients: 20 506 patients ≥ 18 years of age (median age 60 y, 77% men, 87% white) who had ≥ 20 minutes of ischemic symptoms at rest within 6 hours before randomization, and ST-segment elevation ≥ 0.1 mV in 2 limb leads, or 0.2 mV in ≥ 2 contiguous precordial leads, or left bundle-branch block. Exclusion criteria included cardiogenic shock, contraindications to fibrinolysis, receipt of low-molecular-weight heparin in the previous 8 hours, and renal insufficiency. Intervention: Enoxaparin (n = 10 256) or UFH (n = 10 223). The enoxaparin group received placebo UFH plus intravenous (IV) enoxaparin bolus, 30 mg (omitted for patients ≥ 75 y) and 1.0 mg/kg subcutaneously every 12 hours for patients < 75 years; or 0.75 mg/kg every 12 hours for patients ≥ 75 years; or enoxaparin, 1.0 mg/kg per day for creatinine clearance < 30 mL/min, for 8 days or until discharge. The UFH group received placebo enoxaparin plus IV UFH bolus, 60 U/kg body weight, and 12 U/kg per hour infusion for ≥ 48 hours. All patients received fibrinolysis and aspirin. Outcomes: A composite endpoint of death or nonfatal MI at 30 days. Secondary outcomes included major bleeding and various composite endpoints. Patient follow-up: 99.9% (20 479 in the intention-to-treat analysis).