Disopyramide and mexiletine: which is the agent of choice in the long term-oral treatment of lidocaine-responsive arrhythmias? Efficacy comparison in a randomized trial.

Forty patients with serious lidocaine-responsive ventricular arrhythmias were randomly assigned to treatment with either oral disopyramide (100 mg 4 times daily) or mexiletine (200 mg 4 times daily) for 3 weeks. A satisfactory arrhythmias control (greater than 75 % reduction of premature ventricular complexes per minute as compared to the control period prior to lidocaine administration) was achieved in 19 patients in the mexiletine group and in 16 in the disopyramide treated patients. Furthermore, disopyramide failed to maintain the reduction of the number of ventricular extrasystoles per minute obtained with lidocaine, while mexiletine succeeded. Finally, the number of ventricular extrasystoles per minute in the mexiletine treated group was significantly lower than in the other group. Gastrointestinal disturbances were more frequent during mexiletine administration.