Myocardial Recovery in Patients With Systolic Heart Failure and Autoantibodies Against β1-Adrenergic Receptors

BACKGROUND Among various cardiac autoantibodies (AAbs), those recognizing the beta(1)-adrenergic receptor (beta(1)AR) demonstrate agonist-like effects and induce myocardial damage that can be reversed by beta-blockers and immunoglobulin G3 (IgG3) immunoadsorption. OBJECTIVES The goal of this study was to investigate the role of beta(1)AR-AAbs belonging to the IgG3 subclass in patients with recent-onset cardiomyopathy. METHODS Peripheral blood samples were drawn at enrollment in patients with recent-onset cardiomyopathy (left ventricular ejection fraction [LVEF] <= 0.40; <6 months). The presence of IgG and IgG3-beta(1)AR-AAb was determined, and echocardiograms were assessed, at baseline and 6 months. Patients were followed up for <= 48 months. RESULTS Among the 353 patients who had blood samples adequate for the analysis, 62 (18%) were positive for IgG3-beta(1)AR-AAbs (IgG3 group), 58 (16%) were positive for IgG but not IgG3 (non-IgG3 group), and the remaining were negative. There were no significant differences in baseline systolic blood pressure, heart rate, or LVEF among the groups at baseline. Left ventricular end-diastolic and end-systolic diameters were significantly larger in the non-IgG3 group compared with the other groups (left ventricular end-diastolic diameter, p < 0.01; left ventricular end-systolic diameter, p = 0.03). At 6 months, LVEF was significantly higher in the IgG3 group (p = 0.007). Multiple regression analysis showed that IgG3-beta(1)AR-AAb was an independent predictor of LVEF at 6 months and change in LVEF over 6 months, even after multivariable adjustment (LVEF at 6 months, beta = 0.20, p = 0.01; change in LVEF, beta = 0.20, p = 0.008). In patients with high New York Heart Association functional class (III or IV) at baseline, the IgG3 group had a lower incidence of the composite endpoint of all-cause death, cardiac transplantation, and hospitalization due to heart failure, whereas the non-IgG3 group had the highest incidence of the composite endpoint. CONCLUSIONS IgG3-beta(1)AR-AAbs were associated with more favorable myocardial recovery in patients with recent-onset cardiomyopathy. (C) 2017 by the American College of Cardiology Foundation.