Combined analysis of cross‐reacting antibodies anti‐β1AR and anti‐B13 in advanced stages of Chagas heart disease

Objective Autoantibodies cross‐reacting with the β1 adrenergic receptor (anti‐β1AR and anti‐p2β) and cardiac myosin antigens (anti‐B13) have been related to the pathogenesis of chronic Chagas heart disease (CCHD). Studies exploring their levels in different stages are scarce. We aimed to evaluate the relationship of these autoantibodies with the clinical profile of chronic patients, especially regarding their classificatory accuracy in severe presentation with heart failure. Methods and results We conducted a cross‐sectional study of 155 T. cruzi‐seropositive patients and 26 age‐ and gender‐matched healthy controls. They were categorised in three stages of CCHD. Serum antibodies were measured by specific immunoassays. Symptomatic individuals showed increased levels of anti‐β1AR and anti‐B13, while anti‐p2β antibodies were similar between groups. A composite logistic regression model including anti‐B13, anti‐β1AR antibody levels and age was able to predict systolic heart failure yielding an area under the curve of 83% (sensitivity of 67% and specificity of 89%). Conclusions In our study, anti‐β1AR and anti‐B13 antibodies were higher in individuals with chronic Chagas heart disease stage III, mainly in those with dilated cardiomyopathy associated with systolic heart failure. Logistic regression analysis showed that both antibodies were good predictors of severe CCHD. As well as being involved in disease progression, anti‐β1AR and anti‐B13 antibodies may be used as a serum marker of poor prognosis in terms of heart compromise. Objectif Les auto‐anticorps réagissant de façon croisée avec le récepteur adrénergique β1 (anti‐β1AR et anti‐p2β) et les antigènes de la myosine cardiaque (anti‐B13), ont été associés à la pathogenèse de la maladie coronarienne chronique de Chagas (MCCC). Les études explorant leurs taux à différents stades sont rares. Nous avons cherché à évaluer la relation entre ces auto‐anticorps et le profil clinique des patients chroniques, en particulier en ce qui concerne leur précision classificatoire dans la présentation de l'insuffisance cardiaque sévère. Méthodes et résultats Nous avons effectué une étude transversale sur 155 patients séropositifs pour T. cruzi et 26 témoins sains appariés selon l’âge et le sexe. Ils ont été classés en trois stades de MCCC. Les anticorps sériques ont été mesurés par des immunodosages spécifiques. Les individus symptomatiques ont montré des taux accrus d'anticorps anti‐β1AR et anti‐B13, alors que les anticorps