POSTEXERCISE DOPPLER-ECHOCARDIOGRAPHIC HEMODYNAMICS IN IDIOPATHIC DILATED CARDIOMYOPATHY AFTER METOPROLOL INFUSION

1. The physiological effects of the acute administration of a beta-adr enoceptor antagonist in patients with idiopathic dilated cardiomyopath y were; assessed by performing post-exercise Doppler-echocardiography study. Eleven patients and six control subjects were studied. Accordin g to a double-blind randomized protocol, 5 mg of metoprolol or placebo was administered before cycloergometer exercise. 2. In patients, afte r metopolol, a significant decrease in heart rate and systolic blood p ressure, as well as in peak aortic acceleration and cardiac output, wa s observed 2 min after exercise. Left ventricular enddiastolic diamete r did not change from baseline values either after placebo or metoprol ol. In normal subjects, as compared with placebo, a decrease in heart rate and peak aortic acceleration was observed after metoprolol, where as systolic blood pressure did not change. A similar increase in cardi ac output occurred after metoprolol, as compared with placebo, associa ted with an increase in left ventricular enddiastolic diameter and str oke volume. 3. Post-exercise Doppler echocardiography is means of asse ssing haemodynamic changes occurring during exercise in patients with congestive heart failure. Although acute metoprolol administration doe s not provide beneficial haemodynamic effects, a decrease in the energ y requirements of the heart and a faster recovery after exercise may p articipate in the long-term beneficial action of beta-adrenoceptor ant agonists.