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)