[Frequency and prevention of ventricular arrhythmias after acute myocardial infarct]

In a controlled study using mexiletine and placebo, the incidence of ventricular arrhythmias after acute myocardial infarction (AMI) has been compared. The study covered 40 male patients who had sustained AMI and who in the first 48 h after onset of infarction had exhibited ventricular tachycardia, R on T-, multiform or close-coupled ventricular ectopic beats. Half of the patients were given either mexiletine (250 mg 8-hourly) or placebo. On the 4th and 10th day after onset of infarction a continuous 24-hour ECG was performed. 76% of the patients receiving placebo showed serious ventricular arrhythmias compared with 32% receiving mexiletine (p less than 0.05). These results demonstrate (1) the frequency of ventricular arrhythmias in a group of patients already at risk, and (2) the efficacy of an oral antiarrhythmic agent like mexiletine in the management of these rhythm disorders.