Improvement by oral metoprolol of exercise-induced ischemic dysfunction in patients with coronary heart disease

The effect of metoprolol on global left ventricular function during exercise was analyzed with nuclear ventriculography in 17 patients with ischemic heart disease. All had stable angina pectoris and ST-segment depression of more than 0.1 mV during treadmill exercise when not taking metoprolol. Each patient was stressed with supine bicycle exercise to the same load on a maintenance dose of metoprolol (100 mg X 2/day) and on a second occasion without the drug, the two being separated by 7 days. The mean heart rate and systolic blood pressure were significantly reduced both at rest and exercise with metoprolol. There was no significant difference of rest left ventricular ejection fraction with or without metoprolol. At exercise, however, every patient showed improvement of left ventricular function, the average left ventricular ejection fraction increasing by 14% (+/- 6) relative to the same exercise without metoprolol (p less than 0.001). We conclude that chronic metoprolol treatment in patients with ischemic heart disease can ameliorate left ventricular dysfunction induced by exercise and may thereby reduce myocardial ischemia.