- The safety and efficacy of weight-adjusted, low-molecular-weight heparin (dalteparin) was compared with that of unfractionated heparin during 6 days of treatment in 1,482 patients with unstable angina or non-Q-wave myocardial infarction. Dalteparin, at a lower dose, was compared with placebo during the following 39 days. No significant outcome difference was found between the 2 treatment regimens in the unblinded phase (days 1-6). Between days 6-45 the rates of death, myocardial infarction, and recurrence of angina were comparable between the active treatment and placebo groups. The results suggest that twice-daily administration of subcutaneous dalteparin may be an effective and safe alternative to unfractionated heparin during the acute phase of unstable coronary artery disease. Prolonged treatment with dalteparin at a lower once-daily dose did not confer any additional benefit over aspirin (75-165 mg) alone.