Objectives: The aims of this study were to evaluate the effects of beta-blockers on neurohormonal factors in patients with chronic left heart failure (CHF).
Methods: 44 patients, 33 men and 11 women, with age of 60.1 +/- 10.6 years with chronic left heart failure (ejection fraction less or equal to 40% by UCG) were included in this study. All patients received conventional therapy and were randomly assigned either to a bisoprolol or carvedilol group. The dosage of beta-blockers were increased gradually to target or the tolerant dosages (bisoprolol 10 mg qd, carvedilol 25 mg bid) during 3 months in 36 patients. Maintenance dose was continued for 4 months. Plasma concentrations of renin activity (PRA), angiotensin II (Ang II), aldosterone (Ald) and the N-terminal portion of brain natriuretic (NT-proBNP) were assessed with RIA and ELISA at baseline and 3 and 7 months after staring beta-blocker therapy. Left ventricular ejection fraction (LVEF, Modify SIMPSON) was assessed at baseline and 7 months after starting therapy.
Results: (1) In patients with left heart failure, the baseline plasma level of PRA, Ang II and Ald were at normal range. N-terminal BNP concentration was much higher than 200 pg/ml as a result of impaired systolic function, as it elevated with increasing of NYHA grade. (2) The plasma level of NT-proBNP decreased significantly, as compared with that before therapy, but there is no significant change of plasma level of PRA, Ang II and Ald. (3) There were no significant differences between the event group and non-event group for the plasma level of renin-angiotensin and aldosterone during 7 months after starting beta-blocker. The Plasma levels of NT-proBNP were much higher in the event group than non-event group. (4) Multi regression analysis showed that the value of LVEF increased with the decreasing of NT-proBNP levels (beta = -0.389, P = 0.009) and increasing of Ang II level (beta = 0.341, P = 0.020) at baseline. After-therapy LVEF increased with the decreasing of NT-proBNP levels at titration-end (beta = -0.424, P = 0.020).
Conclusions: The plasma level of NT-proBNP is more sensitive and accurate than the plasma level of PRA, Ang II and Ald in evaluation of severity and prognosis of CHF. beta-Blocker administration in patients with CHF decreases circulating levels of NT-proBNP and thus improves left ventricular function, but there is no significant effect on plasma level of PRA, Ang II and Ald.