Efficacy of calcium channel blocker therapy for angina pectoris resulting from small-vessel coronary artery disease and abnormal vasodilator reserve.
Abnormal vasodilator reserve of the coronary microcirculation is a frequent mechanism of angina pectoris in patients with angiographically normal coronary arteries. To assess the effect of calcium channel blocking agents on symptoms and exercise capacity, 26 patients shown to have angina pectoris because of abnormally small coronary arteries and limited vasodilator reserve underwent randomized, double-blind, placebo-controlled outpatient study, with 1 month for each period. An unblinded lead-in phase determined the best dose of verapamil (17 patients) or nifedipine (9 patients). Exercise testing using bicycle ergometry was performed at the end of each period. Four patients interrupted the placebo period and 1 patient interrupted both placebo and drug period because of frequent and severe chest pain. While receiving calcium channel blocker drugs, patients who completed both phases of the study recorded fewer episodes of angina (21 +/- 21 vs 35 +/- 27, p less than 0.001) and consumed fewer nitroglycerin tablets (23 +/- 27 vs 41 +/- 50, p less than 0.001) than during the placebo period. Exercise duration was slightly but significantly prolonged (278 +/- 129 vs 231 +/- 136 seconds, p less than 0.025) during drug treatment compared with placebo, and significantly fewer patients terminated exercise with chest pain while receiving drug treatment. Subjectively, 22 of 26 patients felt better on the calcium channel blocker than on placebo. Thus, calcium channel blocker therapy appears to be beneficial in controlling angina and improving exercise tolerance in patients with angina pectoris resulting from abnormally small coronary arteries and limited vasodilator reserve.(ABSTRACT TRUNCATED AT 250 WORDS)