Angiotensin converting enzyme inhibition in heart failure.

Captopril, the first orally effective converting enzyme inhibitor, was administered to 14 patients with chronic heart failure for 6 week periods, in a double-blind crossover comparison with placebo. Captopril improved symptoms and exercise performance, while left ventricular internal dimensions were reduced. The fall in blood pressure induced by captopril was well tolerated. Glomerular filtration rate was reduced and effective renal plasma flow increased on captopril. No decline in body weight or total body sodium was seen, suggesting that a natriuresis had not occurred. Serum and total body potassium rose. Ventricular arrhythmias declined.