Comparison of captopril with enalapril in the treatment of heart failure: Influence on hemodynamics and measures of renal function

Twenty-nine patients with severe heart failure (NYHA III) were randomly assigned to receive therapy with an angiotensin converting enzyme inhibitor (ACE inhibitor), either captopril or enalapril. The mean daily dosage of captopril was 56±5 mg and of enalapril 9.5±0.4 mg. After a mean of 8±1 days, the influence of both ACE inhibitors on hemodynamics and renal function was compared. The mean arterial pressure in the group treated with captopril (Group A) fell by 9±3 mmHg (p<0.01), and in the group treated with enalapril (Group B) it fell by 12±3 mmHg (p<0.001). The difference between the groups was not significant. Heart rate decreased in both groups; however, the change was significant (p<0.05) only in patients treated with enalapril (−11±3 bpm in Group B vs. −7±4 bpm in Group A). Stroke volume index increased by 6±3 ml/m2 in Group A (p<0.05) vs. 10±2 ml/m2 in Group B (p<0.01). The increase in stroke volume index was not significantly different between the two groups. Mean decreases in pulmonary artery and right atrial pressure were also comparable in both groups. Thus, hemodynamic improvements were similar during therapy with either captopril or enalapril. Serum sodium and potassium before therapy were 137±1 mmol/l and 4.1±0.1 mmol/l, respectively, in group A and 139±1 mmol/l and 4.0±0.1 mmol/l, respectively, in group B. Neither serum electrolytes nor serum creatinine were changed significantly by therapy with captopril or enalapril. These results suggest that despite differences in duration of action the effects on hemodynamics, serum electrolytes, and renal function are similar when comparable dosages of ACE inhibitors are used.