title: Ventricular arrhythmias are related to the presence of autoantibodies with adrenergic activity in chronic chagasic patients with preserved left ventricular function.
abstract: 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 β-adrenergic receptors (Ab-β), 5% activated muscarinic receptors (Ab-M), and 30% activated both muscarinic and β-receptors (Ab-Mβ). In addition, 22.5% of the sera were not reactive (Ab-NR). Ab-β patients presented more cases of arrhythmias in exercise testing (P < .001). In Holter, ventricular arrhythmias appeared more than twice as often in the Ab-β group than in the Ab-NR group and in numbers similar to the Ab-Mβ group (Ab-NR: 2; Ab-β: 5; Ab-Mβ: 3). Arrhythmias were induced by Ab-Mβ in isolated rabbit hearts. Sera from patients with Ab-Mβ, who had longer PR intervals, were able to reversibly prolong PR when perfused in isolated rabbit heart (r² = 0.74; P = .02).
  
  
  CONCLUSIONS
  High prevalence of Ab-β in CChP with preserved left ventricular function led to a greater incidence of ventricular arrhythmias in the patients.
authors.affiliation: Instituto de Biofísica Carlos Chagas Filho, Rio de Janeiro, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Maciel
authors.forename: Roberto C
authors.initials: RC
authors.lastname: Pedrosa
authors.forename: Antonio Carlos
authors.initials: AC
authors.lastname: Campos de Carvalho
authors.forename: Jose H M
authors.initials: JH
authors.lastname: Nascimento
authors.forename: Emiliano
authors.initials: E
authors.lastname: Medei
mesh_terms: D000368:Aged; D000818:Animals; D001145:Arrhythmias, Cardiac / Q000150:complications* / Q000276:immunology / Q000503:physiopathology; D001323:Autoantibodies / Q000276:immunology*; D002598:Chagas Cardiomyopathy / Q000150:complications* / Q000276:immunology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004195:Disease Models, Animal; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000276:immunology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000378:metabolism*; D016277:Ventricular Function, Left / Q000502:physiology*
chemical_list: D001323:Autoantibodies; D011943:Receptors, Adrenergic, beta