LAUSR

BACKGROUND Congenital Complete Heart Block (CCHB), seen in 1:15,000-20,000 births, commonly requires pacemaker placement by young adulthood. There is limited understanding of cardiac morbidity and mortality. OBJECTIVE Determine long-term incidence of cardiac morbidity and mortality in subjects with CCHB and identify associated risk factors. METHODS Retrospective cohort analysis of subjects with CCHB at Children's Hospital of Philadelphia between 1976-2018. The primary outcome is a composite of death, left ventricular systolic dysfunction, heart failure, cardiomyopathy, or cardiac resynchronization therapy (CRT). Cox proportional hazard models assessed independent risk factors for the primary outcome and its components (death, heart failure and/or cardiomyopathy, CRT). RESULTS One-hundred-fourteen subjects (58% female, median age at last visit 15.2 years) were included. Eighty-eight (77%) underwent pacemaker implantation, with median age at placement 1.9 years (IQR, 0.1-8.0 years). Twenty-six subjects (23%) reached the primary outcome - 7 (6%) died and 14 (12%) were diagnosed with heart failure and/or cardiomyopathy. Median time from diagnosis to primary outcome was 3.1 years (IQR, 0.0-10.8 years). There were no significant associations between age at diagnosis less than 1-year (hazard ratio [HR]: 1.5, 95% CI 0.6-3.9), fetal diagnosis (HR: 2.3, 0.96-5.6), or maternal antibody positivity (HR: 2.4, 0.9-6.6) and the primary outcome. Fetal diagnosis had a higher associated hazard of heart failure and/or cardiomyopathy (HR: 4.5, 1.3-15.0). CONCLUSION In 114 subjects with CCHB, 23% reached the composite outcome of cardiac morbidity and mortality, with no significant association between age at diagnosis, fetal diagnosis, and maternal antibody status with composite cardiac morbidity and mortality.