[Clinical analysis of maternal autoantibody-mediated complete left bundle branch block in 9 children].

<b>Objective:</b> To analyze the clinical characteristics, treatment, and outcomes of children with complete left bundle branch block (CLBBB) mediated by maternal autoantibodies. <b>Methods:</b> A retrospective analysis was conducted on nine children diagnosed with maternal autoantibody-mediated CLBBB, treated at Beijing Anzhen Hospital and Fujian Provincial Hospital from March 2015 to August 2023. Their clinical characteristics, electrocardiographic and echocardiographic findings before and after treatment were reviewed. Paired sample <i>t</i>-test was used for inter-group comparison. <b>Results:</b> Among the mothers, 6 had positive antinuclear antibodies (ANA), 5 had anti-Sjogren syndrome antigen A antibodies, and 3 had anti-Ro-52 antibodies. The cohort included one female and eight male children, diagnosed with CLBBB at the age of 1 (2, 13) months. The positive autoantibodies in the infants, consisted with maternal antibodies, were detected within the first 3 months of life among 3 cases. Treatments included anti-heart failure therapy, myocardial nutritional support, intravenous immunoglobulin (IVIG) and glucocorticoids. Before treatment, the levels of troponin I (0.175 (0.060, 10.270) μg/L) and N-terminal pro-B-type natriuretic peptide (420 (327, 12 865) ng/L) were elevated, which normalized in most cases after treatment. Post-treatment, the QRS duration significantly shortened compared to pre-treatment ((137±15) <i>vs.</i>(169±25) ms, <i>t</i>=3.76, <i>P</i><0.001), and the QTc interval significantly decreased ((433±41) <i>vs.</i> (514±27) ms, <i>t</i>=4.95, <i>P</i>=0.001). Before treatment, varying degrees of mitral and tricuspid regurgitation and marked interventricular septal dyskinesia were observed in echocardiography. After treatment, valve regurgitation and ventricular septum motion significantly improved, with a marked increase in left ventricular ejection fraction ((51±13)% <i>vs.</i> (27±6)%, <i>t</i>=-6.66, <i>P</i><0.001). <b>Conclusions:</b> Maternal autoantibody-mediated CLBBB in children presents with chronic heart failure in infancy. Early treatment with anti-heart failure medications, IVIG and glucocorticoids can improve clinical symptoms.