The efficacy and safety of high-dose verapamil and diltiazem in the long-term treatment of stable exertional angina

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Abstract
The efficacy and safety of high‐dose verapamil (480 mg/day) and diltiazem therapy (360 mg/day) were compared in separate cohorts of 26 and 20 patients, respectively. All patients had stable exertional angina and underwent an initial 6‐week double‐blind, placebo‐controlled, randomized phase followed by a 12‐month open‐label period. Angina attacks were reduced by verapamil (6.3±7.5 to 2.5±4.1 attacks per week, p<0.001) and by diltiazem (9.2±7.5 to 3.0±3.1 attacks per week, p<0.001), while treadmill time increased with both verapamil (372±132 to 444±108 s, p<0.001) and diltiazem (412± 175 to 536± 164 s, p<0.001) during the short‐term study. Both agents continued to show similar salu‐tory effects at the end of one year. The beneficial effects of both drugs appeared to be related in part to a reduction of the rate‐pressure product during submaximal exercise (12% by verapamil, 7% by diltiazem, both p<0.05). Adverse effects were few and consisted primarily of mild constipation in six patients taking verapamil, and pedal edema and transient flushing in 2 patients each using diltiazem. Thus, high‐dose verapamil and diltiazem have similar beneficial effects and are safe for the long‐term treatment of effort‐related angina pectoris.