Abrupt change from propranolol to verapamil. Safety and feasibility in stable angina pectoris.

To study the safety and feasibility of abruptly changing antianginal therapy from propranolol hydrochloride to verapamil, we gave propranolol to ten patients with stable angina and coronary artery disease for 14 days, then, on day 15, we began verapamil therapy, which continued for 14 more days. Anginal frequency and nitroglycerin use were similar throughout the study. No patient had symptomatic bradycardia or atrioventricular block. Such crossover therapy is effective when propranolol is replaced by verapamil abruptly.