Double-blind randomized crossover trial of verapamil and propranolol in chronic stable angina

Propranolol (240 mg daily) and verapamil (360 mg daily) were objectively compared for their respective efficacy in the treatment of chronic stable angina pectoris. Twenty-two patients were studied in a randomized placebo controlled, double-blind crossover trial with 4 weeks on each active drug treatment. Multistage treadmill exercise with computer-assisted ECG analysis was performed after 2 weeks on placebo and at the end of each 4-week active drug treatment. The mean exercise time to produce angina was 5.5 minutes (SEM +/- 0.4 minutes) on placebo and this increased to 7.8 (+/- 0.5) minutes on propranolol and 9.1 (+/- 0.5) minutes on verapamil. The improvement in exercise time of verapamil over propranolol was statistically significant (p less than 0.01). Ten patients became free of angina with verapamil and four with propranolol. Resting and maximal exercise heart rates were significantly reduced by propranolol; verapamil did not reduce the maximal heart rate but reduced the resting heart rate slightly. However, the heart rate increase per minute of exercise was significantly diminished (p less than 0.001). ST segment changes showed improvement with both drugs despite marked differences in heart rate profile. The overall efficacy of the slow calcium channel blocker, verapamil, compares favorably with that of a standard beta-adrenoreceptor blocking drug (propranolol), thus providing a new perspective in the management of angina pectoris. These two classes of drugs seem to act by different mechanisms and it is suggested that if patients are resistant or intolerant to one of these drugs, the other can be used to yield a beneficial response.