Autonomic dysfunction and anti-M2 and anti-ß1 receptor antibodies in Chagas disease patients.

BACKGROUND: Sudden death is the leading cause of death in Chagas' disease, affecting patients even in the early stages of the disease. The impairment of the autonomic nervous system in this disease has been recognized, as well as its potential as a trigger for malignant arrhythmias when associated with structural or metabolic changes. OBJECTIVE: We sought to identify, in Chagas patients with preserved systolic function, the impairment of the autonomic nervous system and its association with functionally active anti-m2 and anti-ß1 receptor antibodies. METHODS: Using spectral analysis of RR variability during passive tilt test, chronic chagasic patients were compared with healthy controls matched for age. Subsequently, the association of autonomic dysfunction with functionally active antibodies with anti-m2 and anti-ß1 action was investigated by the Langendorf method. RESULTS: We observed that patients with Chagas disease without ventricular dysfunction express parasympathetic activity against a vagal stimulus, however with less intensity compared to controls. Chagasic patients with anti-m2 or anti-ß1 antibodies showed a further significant reduction of the vagal response during respiratory sinus arrhythmia, regardless of the presence of structural lesion. However, the association of both factors promoted response to vagal stimulation similar to that seen in Chagas disease without their presence. CONCLUSION: The lower vagal reserve in Chagas patients with preserved function was associated with functionally active anti-m2 or anti-ß1 antibodies, and not with the presence of structural heart lesion.

Disfunção autonômica e anticorpos contra receptores anti-m2 e anti-β1 em pacientes chagásicos / Autonomic dysfunction and anti-M2 and anti-β1 receptor antibodies in Chagas disease patients

FUNDAMENTO: A morte súbita é a principal causa de óbito na doença de Chagas, acometendo pacientes mesmo em fases precoces da doença. É reconhecido o comprometimento do sistema nervoso autônomo nessa doença e seu potencial como deflagrador de arritmias malignas quando associado a alterações estruturais ou metabólicas. OBJETIVO: Buscamos identificar, em pacientes chagásicos com função sistólica preservada, o comprometimento do sistema nervoso autônomo e sua associação com anticorpos funcionalmente ativos contra receptores anti-m2 e anti-β1. MÉTODOS: Mediante análise espectral da variabilidade RR durante teste de inclinação passiva, pacientes chagásicos crônicos foram comparados com controles saudáveis pareados por idade. Posteriormente, a associação de disfunção autonômica com anticorpos funcionalmente ativos com ação anti-m2 e anti-β1 foi pesquisada pelo método de Langendorf. RESULTADOS: Observamos que pacientes chagásicos sem disfunção ventricular expressam atividade parassimpática ante um estímulo vagal, porém com menor intensidade em relação aos controles. Pacientes chagásicos com anticorpos anti-m2 ou anti-β1 apresentaram uma redução ainda mais expressiva da resposta vagal durante a arritmia sinusal respiratória, independentemente da presença de lesão estrutural. Entretanto, a associação de ambos promoveu resposta ao estímulo vagal similar aos chagásicos sem a presença dos mesmos. CONCLUSÃO: A menor reserva vagal em pacientes chagásicos com função preservada esteve associada à presença de anticorpos anti-m2 ou anti-β1 funcionalmente ativos, e não à presença de lesão cardíaca estrutural.

BACKGROUND: Sudden death is the leading cause of death in Chagas' disease, affecting patients even in the early stages of the disease. The impairment of the autonomic nervous system in this disease has been recognized, as well as its potential as a trigger for malignant arrhythmias when associated with structural or metabolic changes. OBJECTIVE: We sought to identify, in Chagas patients with preserved systolic function, the impairment of the autonomic nervous system and its association with functionally active anti-m2 and anti-β1 receptor antibodies. METHODS: Using spectral analysis of RR variability during passive tilt test, chronic chagasic patients were compared with healthy controls matched for age. Subsequently, the association of autonomic dysfunction with functionally active antibodies with anti-m2 and anti-β1 action was investigated by the Langendorf method. RESULTS: We observed that patients with Chagas disease without ventricular dysfunction express parasympathetic activity against a vagal stimulus, however with less intensity compared to controls. Chagasic patients with anti-m2 or anti-β1 antibodies showed a further significant reduction of the vagal response during respiratory sinus arrhythmia, regardless of the presence of structural lesion. However, the association of both factors promoted response to vagal stimulation similar to that seen in Chagas disease without their presence. CONCLUSION: The lower vagal reserve in Chagas patients with preserved function was associated with functionally active anti-m2 or anti-β1 antibodies, and not with the presence of structural heart lesion.