[Modification of hemodynamics in tachycardiac atrial fibrillation by metoprolol and verapamil].

Hemodynamic effects of the beta-receptor-blocking agent metoprolol (100 mg orally) and the calcium antagonist verapamil (160 mg orally) were analyzed in 24 patients with atrial fibrillation of different etiology (idiopathic atrial fibrillation, 6 cases; congestive cardiomyopathy, 6 cases; mitral stenosis, 5 cases; mitral regurgitation, 6 cases). 2 h after the administration of either metoprolol or verapamil heart rate was reduced significantly both at rest and during exercise. Cardiac output during exercise was significantly diminished under metoprolol in all groups of patients, whereas no effects were noted under verapamil. Peripheral vascular resistance was significantly decreased by verapamil both at rest and during exercise. No change in total peripheral resistance was noted after metoprolol at rest, but an increase occurred during exercise. Different effects on peripheral circulation may explain the different patterns of cardiac performance observed after heart rate reduction in atrial fibrillation by a calcium antagonist and a beta-blocking agent.