Efficacy of oral mexiletine in the prevention of exercise-induced ventricular ectopic activity.

The anti-arrhythmic effect of oral mexiletine on exercise-induced ventricular arrhythmia was studied in a double blind trial of 10 patients suffering from ventricular ectopic beats of different origins. There was a good reproducibility of the amount of ectopic ventricular activity between consecutive exercise tests when no active drug was given. Treatment for 1 week with mexiletine 600 mg daily resulted in a statistically significant reduction in ventricular ectopic beats, particularly during and after exercise; there were virtually no side-effects. The results suggest that mexiletine has considerable potential in the treatment of ventricular arrhythmias.