Why do patients with congestive heart failure tolerate the initiation of β-blocker therapy?

Abstract

Background. Despite its negative inotropic effects, the initiation of β-adrenergic blockade is tolerated by patients with congestive heart failure (CHF). Accordingly, we examined the acute hemodynamic effects of β-adrenergic blockade on systolic and diastolic left ventricular (LV) function and ventriculo-arterial coupling. In addition, isolated myocardium from patients with CHF shows selective β1-receptor downregulation, implying a greater role for the β2-receptor in maintaining in vivo LV contractility. As a secondary aim, we hypothesized that nonselective β-adrenergic blockade would have greater negative inotropic effect than β1-blockade in patients with CHF. Methods and Results. Patients with clinical CHF (n=24) and control patients without CHF (n=24) were given either the nonselective β-blocker propranolol or the β-selective blocker metoprolol. LV pressure-volume relations were obtained before and after the administration of intravenous β-blocker, and measures of LV systolic and diastolic function were examined. Patients with CHF had a deterioration in LV systolic function with a fall in LV systolic pressure (139±6 to 125±6 mm Hg), cardiac index (2.56±0.11 to 2.20±0.11 mL · min-1 · M-2), dP/dtmax (1173±63 to 897±50 mm Hg/s), and end-systolic elastance (0.88±0.10 to 0.64±0.10 mm Hg/mL), P