Enoxaparin Prevents Death and Cardiac Ischemic Events in Unstable Angina/Non–Q-Wave Myocardial Infarction: Results of the Thrombolysis In Myocardial Infarction (TIMI) 11B Trial

Abstract

Background —Low-molecular-weight heparins are attractive alternatives to unfractionated heparin (UFH) for management of unstable angina/non–Q-wave myocardial infarction (UA/NQMI). Methods and Results —Patients (n=3910) with UA/NQMI were randomized to intravenous UFH for ≥3 days followed by subcutaneous placebo injections or uninterrupted antithrombin therapy with enoxaparin during both the acute phase (initial 30 mg intravenous bolus followed by injections of 1.0 mg/kg every 12 hours) and outpatient phase (injections every 12 hours of 40 mg for patients weighing <65 kg and 60 mg for those weighing ≥65 kg). The primary end point (death, myocardial infarction, or urgent revascularization) occurred by 8 days in 14.5% of patients in the UFH group and 12.4% of patients in the enoxaparin group (OR 0.83; 95% CI 0.69 to 1.00; P =0.048) and by 43 days in 19.7% of the UFH group and 17.3% of the enoxaparin group (OR 0.85; 95% CI 0.72 to 1.00; P =0.048). During the first 72 hours and also throughout the entire initial hospitalization, there was no difference in the rate of major hemorrhage in the treatment groups. During the outpatient phase, major hemorrhage occurred in 1.5% of the group treated with placebo and 2.9% of the group treated with enoxaparin ( P =0.021). Conclusions —Enoxaparin is superior to UFH for reducing a composite of death and serious cardiac ischemic events during the acute management of UA/NQMI patients without causing a significant increase in the rate of major hemorrhage. No further relative decrease in events occurred with outpatient enoxaparin treatment, but there was an increase in the rate of major hemorrhage.