Comparable effects of oral diltiazem and verapamil in the treatment of hypertrophic cardiomyopathy. Double-blind crossover study.

The effects of oral diltiazem, 180 mg/day, were compared with those of oral verapamil, 240 mg/day, in 32 patients with hypertrophic cardiomyopathy (HCM), using a double-blind crossover study design. In the first treatment period, diltiazem and verapamil improved subjective complaints in 83% and 71% of those who were symptomatic in the baseline period. Maximal oxygen consumption on exercise stress test increased with verapamil by 2.9 +/- 4.2 ml/Kg/min (p less than 0.05), and tended to increase with diltiazem. Verapamil also reduced the amplitude of negative T wave. In the statistical analysis based on the crossover design, diltiazem and verapamil did not differ in global improvement, overall safety and global utility ratings. In addition, both drugs showed comparable effects on electrocardiographic and echocardiographic variables and exercise tolerance except for minor differences in diastolic blood pressure, T wave amplitude and peak exercise heart rate. On the other hand, verapamil tended to induce more serious side effects, forcing the discontinuation of medication in 3 patients. Therefore, the present study indicates that diltiazem is essentially equally as effective as verapamil and is preferable in the treatment of patients with HCM since it may exhibit fewer serious side effects.