Complete heart block in neonatal lupus: a forgotten cause of fetal bradycardia

The most common cause of congenital heart block (CHB) is neonatal lupus, an acquired autoimmune disease caused by transplacental transfer of maternal antibodies to the fetus. A full-term female neonate was admitted to neonatal intensive care unit for severe bradycardia with stable haemodynamics. The mother, showing no clinical symptoms or any particular history, was transferred to our tertiary centre for profound fetal bradycardia. At birth, the infant's ECG showed a third-degree atrioventricular block and echocardiography was normal. Cardiac neonatal lupus was confirmed with positive maternal anti-Ro antibodies. Under close monitoring, the infant tolerated the bradycardia well (median 67 beats per minute (bpm)) and was discharged on day 6 of life. There was no indication for pacemaker, but she would be on regular follow-up with a paediatric cardiologist. This article holds an important insight as it is the first confirmed case of autoimmune CHB in Cambodia in which the mother's antibody was found only after diagnosis on the neonate.