Comparative Trial of Mexiletine and Lignocaine in the Treatment of Early Ventricular Tachyarrhythmias After Acute Myocardial Infarction

The antiarrhythmic effects of intravenously administered lignocaine and mexiletine were compared over a period of 48 hr in a randomized trial on 24 patients who developed ventricular tachyarrhythmias within 48 hr of the onset of acute myocardial infarction. Mexiletine was given as an initial bolus of 200 mg, followed by an infusion of 1 mg/min reduced to 0.5 mg/min after 1 hr. Lignocaine was given as a bolus of 100 mg, followed by an infusion of 3 mg/min reduced to 2 mg/min after 1 hr. Plasma levels of mexiletine, lignocaine, and monoethylglycinexylidide were monitored. The frequency of "complex" ventricular tachyarrhythmias was significantly lower in the mexiletine-treated group. This group of patients also had significantly fewer ventricular extrasystoles than those receiving lignocaine, the difference being most marked during the second 24 hr of treatment. Too few episodes of ventricular fibrillation occurred for statistical comment. The greater efficacy of mexiletine was not associated with increased drug toxicity.