Combination antiarrhythmic treatment among class Ia, Ib, and II agents for ventricular arrhythmias.

Ventricular arrhythmia suppression trials were performed to compare the efficacies and side effects of disopyramide and mexiletine used alone and in combination, and to compare the efficacies and side effects of mexiletine and propranolol used alone and in combination, in patients with chronic ventricular premature contractions (VPCs, greater than or equal to 3000 beats/day). The study on the combination of disopyramide and mexiletine included 26 patients (19 men and 7 women). Disopyramide 100 mg tid or mexiletine 150 mg tid was administered as single-drug therapy, and disopyramide 50 mg plus mexiletine 100 mg tid was administered as combination therapy. Each patient underwent Holter monitoring during four different periods: baseline, disopyramide alone, mexiletine alone, and combination therapy. The mean number of VPCs/hr at baseline was 796 +/- 522 (mean +/- SD), which was significantly decreased with all three therapies (p less than 0.01 in each) to a) 415 +/- 480 with disopyramide alone, b) 341 +/- 368 with mexiletine alone, and c) 345 +/- 408 with the combination therapy. The number of patients demonstrating a significant reduction in VPCs (greater than or equal to 75%) and the elimination of ventricular tachycardia (VT; three or more consecutive VPCs) did not differ significantly among the three therapies. The prematurity index (PI), vulnerability index (VI), and QTc tended to be aggravated by disopyramide therapy alone, but these values were corrected by combination therapy. No patients withdrew from the study due to side effects during combination therapy, although three patients withdrew from the study due to severe side effects during single-drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)