Late-Onset Dilated Cardiomyopathy in Auto Immune-Mediated Complete Congenital Heart Block: A Case Report

Abstract

Complete congenital heart block (CHB), a rare and fatal bradyarrhythmia observed in children, carries significant mortality and morbidity. When congenital heart block occurs in isolation with a structurally normal heart, it prompts suspicion of an autoimmune etiology, wherein maternal antibodies are transmitted transplacentally, impacting the fetal conducting system. The manifestation of congenital complete atrioventricular block (CCAVB) can lead to complications such as dilated cardiomyopathies, arrhythmias, and fibroelastosis in certain cases. Notably, dilated cardiomyopathy is a significant prognostic factor in children diagnosed with congenital heart block. Pathological investigations have revealed the presence of antibodies, complements, and indicators of inflammation or fibrosis across the myocardium, emphasizing the shared molecular mechanisms between CCAVB and the development of dilated cardiomyopathy (DCM). This article presents the case of a one-year-old female child who presented with signs of dilated cardiomyopathy, later identified through retrospective evaluation as having autoimmune congenital heart block. The mother of the child was diagnosed with Sjogren's syndrome, characterized by positive anti-RO titers. Remarkably, the child remained asymptomatic for a year without the need for pacing intervention. The child's condition was successfully stabilized with appropriate treatment, and plans for pacemaker insertion will be considered once specific criteria are met. The onset of cardiomyopathy in a known case of CCAVB should serve as a crucial alert for prognostic considerations and the potential necessity for early-pacing intervention.

Keywords: atrioventricular block; congenital heart block; dilated cardiomyopathy; pediatrics & neonatology; sjogren's.

Figure 1. ECG showing complete congenital heart block

Black arrows indicate P waves, and orange arrows indicate QRS complexes, which are independent of P waves.