Acute hemodynamic effects and tolerability of intravenous amiodarone, 5 mg/kg administered over 5 minutes, were compared in patients with coronary artery disease and either a normal (left ventricular [LV] ejection fraction greater than or equal to 45%, n = 10, group N) or impaired LV function (ejection fraction less than 45%, n = 9, group L). Amiodarone reduced systemic vascular resistence and LV and aortic pressures in both groups (13%, 18%, and 13%, respectively [group N], and 15%, 17%, and 15%, respectively [group L]) over the short term. Heart rate initially increased (18%, group L, and 10% group N), but was followed by a late 6% decrease in group N only, and by a progressive reduction in contractility (Vmax), together with a rise in LV end-diastolic pressure (19% and 38%, respectively [group N] and 17% and 58%, respectively [group L]; all values p less than 0.05 versus control). Coronary flow increased significantly by 20% (group N) and 31% (group L), but only during amiodarone administration, accompanied by a 26% and 25% reduction in myocardial oxygen extraction in groups N and L, respectively. Stroke work decreased in both groups (20% [group N] and 19% [group L], p less than 0.05 versus control). In contrast, cardiac output only improved (10%) in patients with impaired ventricular function. Significant side effects did not occur. Thus relatively high dosages of intravenous amiodarone are well tolerated and improve cardiac pump function in patients with an impaired, but not with a normal cardiac function. However, the tendency to increase LV end-diastolic pressures necessitates careful monitoring in patients in whom preexisting LV filling pressure may be elevated.