Intravenous amrinone in left ventricular failure complicated by acute myocardial infarction.

Hemodynamic dose-response effects of intravenous amrinone were studied in 22 male patients aged 38 to 62 years with left ventricular failure occurring within 18 hours of acute myocardial infarction. After hemodynamic confirmation of a raised left-sided cardiac filling pressure--pulmonary artery occluded pressure greater than 20 mm Hg--patients were randomized to either low-dose infusion of amrinone (200 micrograms/kg/hr for 30 minutes, 400 micrograms/kg/hr for 30 minutes and then 800 micrograms/kg/hr for 30 minutes) or high-dose infusion of the drug (800, 1,600 and 3,200 micrograms/kg/hr sequentially, each for 30 minutes). Hemodynamic measurements were obtained at 1 hour before amrinone and at the end of each infusion step. Low-dose infusion of amrinone resulted in a progressive increase in cardiac output (p less than 0.05) and stroke volume (p less than 0.05) and progressive reductions in pulmonary artery occluded pressure (p less than 0.01) and systemic vascular resistance (p less than 0.05). Systemic blood pressure and heart rate were unchanged. High-dose infusion resulted in a similar increase in cardiac output (p less than 0.05) but no change in stroke volume owing to associated tachycardia (p less than 0.01). There was a significantly greater decrease in pulmonary artery occluded pressure compared with the low-dose infusion (p less than 0.05), and systemic arterial diastolic and mean pressures were also decreased (p less than 0.05). The decrease in systemic vascular resistance was of a similar order to that induced by the low-dose infusion.(ABSTRACT TRUNCATED AT 250 WORDS)