Long-term antianginal action of verapamil assessed with quantitated serial treadmill stress testing.

The long-term efficacy of verapamil in a dose of 360 mg daily in patients with chronic stable angina pectoris was assessed by quantitated serial treadmill exercise tests. Twenty-eight patients were investigated with a placebo-controlled, double-blind, crossover protocol of 2 weeks each and afterward all patients were put on long-term therapy. Exercise tests were performed at the end of the placebo period and after 2, 4, 8, 16, 24 and 52 weeks of verapamil therapy. All 28 experienced angina during treadmill tests on placebo and the mean (+/- standard error of the mean) exercise time was 6.6 +/- 0.5 minutes. This increased to 9.2 +/- 0.8 minutes at 2 weeks and 50 11.2 +/- 0.8 minutes at 4 weeks. Fifteen and 20 of the 28 patients became angina-free during treadmill exercise at 2 and 4 weeks, respectively. The consumption of nitroglycerin showed a similar improvement. The improvement was maintained at 1 year of follow-up. The on-line computer-analyzed S-T segment changes showed a statistically significant improvement at all follow-up periods. Withdrawal of verapamil produced a return to pretreatment levels. The adverse effects noted were constipation in seven patients and reversible P-R interval prolongation in two. No heart failure occurred in any patient. These findings suggest that verapamil possesses a powerful and sustained antianginal action and, in a dose of 360 mg daily, merits a place as a primary therapeutic agent in the management of chronic stable angina.