Effect of propranolol on ventricular arrhythmia. The beta-blocker heart attack trial experience

The Beta-Blocker Heart Attack Trial (BHAT) was a multicenter, randomized, double-blind, placebo-controlled trial that tested the effectiveness of propranolol in reducing the mortality rate in patients after myocardial infarction (MI). Twenty-four hour ambulatory ECG monitoring was done on 3279 of the 3837 enrolled patients at baseline (5-21 days after hospital admission) and repeated after 6 weeks of therapy in a random sample of 25% of the study population. Ventricular arrhythmias were divided into seven different categories and the prevalence of each category is presented. Ventricular arrhythmia at baseline appears to increase with patient age, past history of myocardial infarction, and use of diuretics. Other selected variables--sex, CPK ratio and history of smoking, diabetes and hypertension--appear to be less clearly associated with ventricular arrhythmia. Paired data analysis performed on 826 patients who had ambulatory electrocardiograms both at baseline and after 6 weeks of treatment showed an increased prevalence of ventricular arrhythmia at 6 weeks. This increase was blunted by propranolol therapy.