Effects of the cardioselective beta adrenergic receptor blocking agent metoprolol in angina pectoris. Subacute study with exercise tests

Abstract

The effect of a cardioselective beta adrenergic blocking agent, metoprolol, on symptoms and exercise tolerance was studied in 16 patients with angina pectoris. Metoprolol was compared with placebo at 2 dose levels (20mg t.d.s. and 50mg t.d.s.) in a double blind trial in 14 patients. Compared with placebo, metoprolol caused a significant reduction of heart rate and systolic blood pressure during exercise, and consequently a reduction of the rate pressure product. The reduction was greater with 50 mg t.d.s. than with 20mg t.d.s. The exercise tolerance was measured as total work increased significantly by 21% during treatment with metoprolol 20 mg t.d.s., and by 17% during treatment with 50mg t.d.s. There was a reduction in the number of anginal attacks and in nitroglycerin consumption, and subjective improvement of angina pectoris at both dose levels of metoprolol. No signs of cardiac failure appeared during any of the 4 treatment periods. Heart volume showed no significant change. Unwanted effects were of the same frequency and severity during treatment with metoprolol at both dose levels as with placebo. The 16 patients were included in a long term tolerance study with unchanged doses of metoprolol and have now been followed for 14 mth without any unwanted effects.