Enalapril: A new angiotensin-converting enzyme inhibitor in chronic heart failure: Acute and chronic hemodynamic evaluations

Hemodynamic effects of the new oral angiotensin-con-verting enzyme inhibitor, enalapril, were evaluated acutely in 15 patients with chronic heart failure and in 7 patients after 4 weeks of maintenance therapy. Initial hemodynamic effects were characterized by a significant increase in cardiac index (from 2.1 ± 0.7 to 2.6 ± 0.7 liters/min per m2) and a decrease in pulmonary capillary wedge pressure (from 30 ± 6 to 24 ± 7 mm Hg), right atrial pressure (from 14±5 to 11±4 mm Hg), mean arterial pressure (from 96 ± 16 to 80 ± 17 mm Hg) and systemic vascular resistance (from 1,820 ± 480 to 1,200 ± 410 dynes s cm-5) without any significant change in heart rate, pulmonary artery pressure and pulmonary vascular resistance.During maintenance therapy, the dose of diuretic drugs had to be increased because of systemic venous hypertension. Repeat hemodynamic study showed that after chronic therapy, cardiac index (2.1 ± 0.7 vs. 3.0 ± 0.08 liters/min per m2) and stroke volume index (24 ± 10 vs. 36 ± 7 ml/m2) remained elevated and pulmonary capillary wedge pressure was lower than control (30 ± 6 vs. 16 ± 6 mm Hg), indicating sustained improvement in left ventricular performance. Plasma renin activity increased and plasma norepinephrine levels decreased after enalapril therapy and these humoral changes persisted during maintenance therapy.All patients receiving chronic therapy had symptomatic improvement. Significant hypotension, which occurred in five patients at the initiation of therapy, appears to be the major side effect. These findings suggest that enalapril has the potential to improve the cardiac performance of patients with chronic heart failure, and further clinical studies are warranted