Nifedipine therapy for stable angina pectoris: Preliminary results of effects on angina frequency and treadmill exercise response

Ten patients with stable angina pectoris secondary to atherosclerotic coronary artery disease received nifedipine (10 mg and 20 mg orally three times daily, each for 2 weeks) or placebo (for 2 weeks) in a single-blind manner during a 6 week period. One patient was excluded because nocturnal and resting angina developed while he was receiving placebo. The frequency of anginal attacks in the remaining nine patients decreased from 11.2 ± 2.2 (mean ± standard error of the mean) per patient per week during administration of placebo to 7.1 ± 1.6 during therapy with nifedipine at 10 mg and to 6.3 ±1.7 during administration of 20 mg of nifedipine (P < 0.05 for both doses of active drug versus placebo). Nitroglycerin consumption similarly decreased from 8.9 ± 2.3 tablets per patient per week (placebo) to 4.8 ± 1.4 tablets during administration of 10 mg of nifedipine and to 4.2 ± 1.2 during therapy with 20 mg of the drug (P < 0.05 for both doses of drug versus placebo). Duration of treadmill exercise increased from 368 ± 50 seconds (placebo) to 471 ± 72 seconds at the 10 mg dose of nifedipine and 522 ± 79 seconds at 20 mg (P < 0.05 for both doses versus placebo). Maximal S-T segment shift and product of heart rate × systolic blood pressure did not differ between the placebo period and that of active drug therapy. Treadmill exercise performed during subsequent double-blind, randomized crossover treatment with placebo and nifedipine revealed increased exercise duration after nifedipine therapy (524 ± 49 seconds) compared with that after placebo (462 ± 52 seconds) (P < 0.005) but, again, maximal S-T shift and the product of heart rate × systolic blood pressure did not differ. Side effects from nifedipine were minor and easily tolerable. The results seem to indicate that nifedipine prolongs exercise time by decreasing heart rate × systolic blood pressure product at a given work load, possibly in a manner similar to that of long-acting nitrate therapy.