Effects of metoprolol in angina pectoris. A subacute study with exercise tests and a long-term tolerability study.

Eighteen patients with angina pectoris, who had previously participated in a cross-over study with 20 mg metoprolol t.i.d. and placebo, have been included in this study. During an introductory six-month open tolerability study, all patients were treated with 50 mg metoprolol t.i.d. and during a subsequent cross-over study, the efficacy of this dose was compared with that of placebo under double-blind conditions. An exercise was performed at the end of each cross-over period. Metoprolol, in a dose of 50 mg t.i.d., gave a significant improvement compared with placebo in respect of the number of anginal attacks, nitroglycerin consumption and daily subjective assessment of the patients' anginal symptoms. Metoprolol also gave a significant increase in exercise capacity, both until the appearance of 1 mm ST segment depression and until the end of exercise. Heart rate and blood pressure were reduced both at rest and during exercise. No severe unwanted effects were observed during this study ranging over eight months, and none of the patients had any signs or symptoms of cardiac failure or pulmonary dysfunction on any occasion. Unwanted effects reported were mild to moderate, and the frequency was the same as during placebo treatment. No abnormal laboratory findings were observed and the relative heart volume was not significantly changed. Administration of 50 mg metoprolol t.i.d. seems to be of greater benefit than 20 mg metoprolol t.i.d., previously investigated in these patients.