Verapamil in effort-induced angina pectoris in patients with normal coronary arteries

Acute coronary vasomotor effects of nifedipine and therapeutic correlates in syndrome X

In 18 patients (12 women) presenting with effort-induced chest pain and normal coronary angiograms (syndrome X), 10 mg sublingual nifedipine increased the lumen of major coronary arteries (quantitative angiography) by 13 +/- 10% (p less than 0.01), coronary blood flow (thermodilution) by 23 +/- 26% (p less than 0.05), norepinephrine plasma concentration by 60 +/- 42% (p less than 0.01) and decreased the global ST-segment shift during the effort stress test from 8.8 +/- 4.1 to 7 +/- 6.8 mm (p less than 0.03) at comparable maximal workload and at unchanged double product. There was a correlation (positive) of changes in flow with changes in coronary lumen diameter (r = 0.65, p less than 0.01) with ST-segment response to exercise (r = 0.83, p less than 0.001) and with (inverse) norepinephrine plasma concentration (r = -0.70, p less than 0.01); no correlation was found between ST-segment response and changes in arterial lumen diameter. In a few cases, nifedipine did not improve or even worsened the response to exercise; coronary flow was unchanged or decreased and norepinephrine plasma levels were modestly or greatly increased, respectively. After 4 weeks of treatment with nifedipine (10 to 20 mg 4 times daily), the effort ST-segment shift was further decreased to 4.4 +/- 3.5 mm (p less than 0.03) despite a slightly increased double product. Plasma norepinephrine values, as compared to those after acute nifedipine, were decreased by 40% in patients with further improvement and were unchanged in patients whose exercise performance did not vary.(ABSTRACT TRUNCATED AT 250 WORDS)

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)