Plasma free fatty acids and the incidence of arrhythmias in acute myocardial infarction during treatment with small doses of subcutaneous heparin or warfarin.

In a prospective trial, 99 patients with a history of AMI of less than 12 hours were allocated at random to treatment with subcutaneous heparin, 5 000 IU twice daily, (51 patients) or warfarin (48 patients). In a subsample of 21 patients, 11 in the warfarin group and 10 in the heparin group, fasting FFA analyses were performed before and 2 hours after administration of anticoagulants on days 1 and 2. No measurable increase in FFA concentrations was demonstrated in the heparin-treated patients, in spite of a significant influence on the thrombin clotting time. The frequency of ventricular arrhythmias as detected by continuous tape recordings was equal in the two groups. It is concluded that subcutaneous heparin, 5 000 IU every 12 hours, can be administered to patients with AMI without increasing the risk of arrhythmias as compared with warfarin.