Changes in pulmonary hemodynamics predict benefits in exercise capacity after ACE inhibition in patients with mild to moderate congestive heart failure

Abstract

Several causes may affect the efficacy of angiotensin‐converting enzyme (ACE) inhibitors in congestive heart failure (CHF). The present study was undertaken to identify what factors might predict benefits in exercise capacity after ACE inhibition in 22 patients with mild to moderate CHF. All patients underwent hemodynamic evaluation before and following an oral dose of quinapril (20 mg). They were then treated daily with 20 mg of quinapril and underwent exercise stress test off‐drugs 1 day and 6 months later. Patients were grouped according to their relative changes in vascular resistances after quinapril: Group A (n=15) showed a greater decrease in pulmonary vascular resistance (PVR) than in systemic vascular resistance (SVR) (%ΔPVR/%ΔSVR>1). The opposite occurred in Group B (n = 7). Comparison of pretreatment baseline features revealed that the two groups had similar biochemical and hormonal variables, cardiac index, and SVR. Conversely, Group A patients had higher (p<0.05) pulmonary artery pressure and PVR compared with Group B patients. Following quinapril, Group A patients showed a greater (p<0.05) increase in cardiac index than Group B patients, despite a similar reduction in SVR. Accordingly, 1‐day drug treatment significantly (p<0.001) increased exercise duration in Group A (+29%), but not in Group B patients (+7%). Benefits in exercise capacity were still significant (p<0.001) 6 months later. It is concluded that (1) ACE inhibitors may significantly increase exercise capacity in most but not all CHF patients; (2) these salutary effects occur predominantly in patients with abnormal pulmonary hemodynamics; (3) although there are many possible mechanisms by which these drugs may benefit CHF, these data favor the effects on veins and/or pulmonary vasculature as being the most clinically important factor. Copyright © 1993 Wiley Periodicals, Inc.