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 angio tensin-converting enzyme inhibitor (captopril) treatment on neurohormonal f unction in a randomized prospective study on patients with heart failure du e 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) fu nctional 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) concentra tion 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 an d the patients were re-investigated 1 month thereafter, Results. The mean level of PRA was normal at baseline, reduced during thera py with metoprolol, and increased during therapy with captopril. The mean p lasma concentration of A II was reduced during exercise and there was a tre nd towards a reduction even at rest in the metoprolol group, but not in the captopril group, The urinary excretion of aldosterone decreased in both gr oups. The mean plasma concentration of ANP was elevated at baseline and dec lined during exercise in the metoprolol group. Conclusion, In patients with dilated cardiomyopathy and only a partly activ ated renin-angiotensin system, both metoprolol and captopril reduced urinar y excretion of aldosterone. Furthermore, metoprolol suppressed the exercise -induced increase in ANP, suggesting a favourable effect on ventricular per formance.