Ventricular Arrhythmias are Related to the Presence of Autoantibodies With Adrenergic Activity in Chronic Chagasic Patients With Preserved Left Ventricular Function

Background: The presence of G-type immunoglobulins with functional activity was previously demonstrated in chronic chagasic patients (CChP) with heart failure. Here we evaluated the profile and the arrhythmogenic effects of sera from CChP with preserved ventricular function. Methods: Electrocardiography (ECG), Holter monitoring, exercise testing, and left ventricular ejection fraction of 40 CChP were measured. Serum from each patient was characterized in isolated rabbit hearts where ECG parameters were analyzed. Results: From the total sera of the 40 CChP tested in rabbit hearts, 42.5% activated beta-adrenergic receptors (Ab-beta), 5% activated muscarinic receptors (Ab-M), and 30% activated both muscarinic and beta-receptors (Ab-M beta). In addition, 22.5% of the sera were not reactive (Ab-NR). Ab-beta patients presented more cases of arrhythmias in exercise testing (P < .001). In Holter, ventricular arrhythmias appeared more than twice as often in the Ab-beta group than in the Ab-NR group and in numbers similar to the Ab-M beta group (Ab-NR: 2; Ab-beta: 5; Ab-M beta: 3). Arrhythmias were induced by Ab-M beta in isolated rabbit hearts. Sera from patients with Ab-M beta, who had longer PR intervals, were able to reversibly prolong PR when perfused in isolated rabbit heart (r(2) = 0.74; P = .02). Conclusions: High prevalence of Ab-beta in CChP with preserved left ventricular function led to a greater incidence of ventricular arrhythmias in the patients. (J Cardiac Fail 2012;18:423-431)