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.
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine