Abstract 3154: Presence of Autoantibody Directed against β-adrenergic Receptors is Associated with Amelioration of Cardiac Dysfunction during β-blocker Therapy for Congestive Heart Failure
Background: Autoimmune disorder is one of the features characterizing congestive heart failure (CHF) not only due to idiopathic dilated cardiomyopathy (IDC) but due to other etiologies. Autoantibody directed against β1-adrenergic receptors exerts agonist-like action inducing receptor uncoupling, and elicits persistent myocardial damage as well as fatal ventricular arrhythmias in such patients. Previous studies from our laboratoy have shown that β-adrenergic receptor blockers might affect biological actions of the autoantibody. We, therefore, attempted to determine the significance of the presence or absence of autoantibody against β1-adrenergic receptors in patients with CHF who received β-adrenergic receptor blockers.
Methods and materials: Eighty-two CHF patients (age 62± 12 years old, NYHA class II, n=63; III, n=18; IV, n=1; Male 71, Female 11; IDC, n=63; ischemic heart disease, n=16; valvular heart disease, n=3) were enrolled. They were randomly assigned to metoprolol group (n=38) and carvedilol group (n=44), and received β-blocker therapy for 16 weeks. Sera were collected and presence or absence of the antibody was determined using ELISA.
Results: Autoantibody was found to be positive in 15 (18%) out of the study population (P), and negative in the remaining 67 patients (N). Carvedilol was given in 9 patients in P and 35 patients in N (60% vs. 52%, NS). Etiologies of CHF were also similar between P and N (%IDC, 86% vs. 75%, NS). Change in left ventricular end-diastolic dimension from baseline value tended to be larger in P than N (−0.5± 0.5 cm vs. −0.2 ± 0.4 cm, p=0.09). Change in end-systolic dimension was significantly larger in P than N (−0.9 ± 0.8 cm vs. −0.4 ± 0.6 cm, p = 0.02). Change in left ventricular ejection fraction measured by radionuclide ventriculography (LVEF) from baseline was greater in P than N (+16 ± 12% vs. +9 ± 9%, p=0.02). Change in plasma brain natriuretic peptide level from baseline was also larger in P than N (−64.7 ± 126.5 pg/ml vs. −19.6 ± 218.9 pg/ml, p=0.02).
Conclusions: Our study data suggest that β-blocker therapy is more effective in alleviating cardiac dysfunction and reversing remodeling in patients with autoantibody directed against β1 adrenergic receptors.