Immediate effects of captopril in acute left ventricular failure secondary to myocardial infarction.

In eight patients with acute left ventricular failure secondary to myocardial infarction the haemodynamic effects of captopril (25 mg), an orally active converting enzyme inhibitor, were measured. Haemodynamic modifications were maximal at 60 min and lasted for 2-3 h. Pulmonary wedge pressure fell from 23.5 +/- 4.9 (mean +/- SD) to 16.8 +/- 4.7 mmHg (P less than 0.01), cardiac output rose from 3.24 +/- 1 to 4.05 +/- 0.91 1/min (P less than 0.01). Systemic vascular resistance decreased from 27.34 +/- 3.81 to 17.52 +/- 1.65 mmHg min l-1 (P less than 0.01). Mean arterial pressure fell from 89.6 +/- 13.9 to 75.7 +/- 16.3 mmHg (P less than 0.001) while heart rate was not significantly modified. Six patients who had high pretreatment plasma renin activity values responded by a decrease in ventricular filling pressure and/or an increase in cardiac output. One patient with normal initial plasma renin activity value showed similar haemodynamic effects. THese data suggest that in the short term captopril is a vasodilator with both arterial and venous effects and improves cardiac function in acute left ventricular failure secondary to myocardial infarction.