Small Doses of Subcutaneous Heparin, Plasma Free-Fatty-Acids, and the Incidence of Ventricular Arrhythmias in Patients with Acute Myocardial Infarction

The frequency of deep vein thrombosis (DVT) diagnosed with the 125I-fibrinogen technique in patients with acute myocardial infarction (AMI) has been found to be reduced frcm about 20% without anticoagulation to about 5% with warfarin or small doses of subcutaneous heparin.A somewhat higher incidence of ventricular tachycardia in patients with AMI treated with small doses of subcutaneous heparin has been reported. A possible mechanism might be heparin-induced activation of lipoprotein lipase with consequent increase of plasma free-fatty-acids (FFA), which have been found to be arrhythmogenic in patients with AMI.In the present prospective trial, 99 patients with AMI and a history of less than 12 hours were allocated at random to treatment with subcutaneous heparin 5000 IU twice daily, or warfarin. In a randomized subsample of 21 patients fasting FFA analyses were performed before and 2 hours after the administration of anticoagulants on day 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 continous tape recordings was equal in the two treatment groups.It is concluded that subcutaneous heparin 5 000 IU every 12 hours seems to be a safe measures of prophylaxis against venous thromboembolic ccmplications in patients with AMI.