The circulating renin-angiotensin system during treatment with metoprolol or captopril in patients with heart failure due to non-ischaemic dilated cardiomyopathy

Objective, To investigate the effects of beta-blocker (metoprolol) or angiotensin-converting enzyme inhibitor (captopril) treatment on neurohormonal function in a randomized prospective study on patients with heart failure due to dilated cardiomyopathy, Patients. Fifty-four patients (42 men and 12 women, mean age 50 years) were studied. There were three patients in NYHA (New York Heart Association) functional class I, 32 patients in class II and 19 patients in class III. Methods, Measurements of plasma renin activity (PRA), plasma angiotensin II (A II) concentration and plasma atrial natriuretic peptide (ANP) concentration were made at rest and also in a subgroup (n = 32) during exercise. The urinary excretion of aldosterone was also determined. Investigations were performed at baseline,and after 3 and 6 months, Therapy was then stopped and the patients were re-investigated 1 month thereafter, Results. The mean level of PRA was normal at baseline, reduced during therapy with metoprolol, and increased during therapy with captopril. The mean plasma concentration of A II was reduced during exercise and there was a trend towards a reduction even at rest in the metoprolol group, but not in the captopril group, The urinary excretion of aldosterone decreased in both groups. The mean plasma concentration of ANP was elevated at baseline and declined during exercise in the metoprolol group. Conclusion, In patients with dilated cardiomyopathy and only a partly activated renin-angiotensin system, both metoprolol and captopril reduced urinary excretion of aldosterone. Furthermore, metoprolol suppressed the exercise-induced increase in ANP, suggesting a favourable effect on ventricular performance.