Effects of a new calcium antagonist, mibefradil (Ro 40-5967), on silent ischemia in patients with stable chronic angina pectoris: A multicenter placebo-controlled study

Objectives. The purpose of this study was to evaluate the effects of mibefradil (Ro 40-5967) on the frequency and duration of episodes of asymptomatic ischemia in patients with stable angina pectoris and to determine the most efficient single therapeutic dose of this drug. Background. Mibefradil is a novel calcium channel antagonist that shows a high bioavailability, induces no reflex tachycardia and has no negative inotropic effects. Methods. In a multicenter, double-blind, placebo-controlled, parallel design trial, 126 patients with chronic stable angina pectoris were studied. After 1 week of a placebo run-in period, patients were randomized to receive 25, 50, 100, 150 mg of mibefradil or placebo for 2 weeks, Ambulatory 48-h electrocardiographic (EGG) monitoring was performed at the end of both the placebo run in period and the active treatment period. Results. Compared with placebo, mibefradil was associated with significantly less ischemia as manifested during ambulatory ECG monitoring. In the 150- and 100-mg groups, respectively, the drug resulted in a 73% and 63% reduction in the frequency of episodes of ST segment depression and a 78% and 58% reduction in the total duration of ST segment depression. Highly significant linear dose-response relations were present across all treatment groups for ischemic episodes and ischemia duration (p < 0.001). Electrocardiographic abnormalities related to treatment were first-degree atrioventricular block, sinus bradycardia and short Wenckebach episodes, observed during sleep on Holter monitoring. All ECG events were dose related. Conclusions. Mibefradil is a new, safe, well tolerated and very effective dose-dependent anti-ischemic calcium channel antagonist.