Recurrent Congenital Heart Block Due to Maternal Anti-Ro Antibodies: Successful Prevention of Poor Pregnancy Outcome with Hydroxychloroquine and Added Dexamethasone

Autoimmune Congenital Heart Block (CHB) is an immune-mediated disease caused by transplacental passage of maternal circulating anti-Ro/SSA and anti-La/SSB antibodies which can bind to fetal cardiac tissue, damaging conduction tissues by inflammation and fibrosis. Approximately 2% of pregnancies with positive anti-Ro antibodies will be complicated by fetal atrioventricular block and the risk of recurrence in subsequent pregnancies is 10 times higher. We report a case of a clinically asymptomatic patient diagnosed with anti-Ro antibodies who had two pregnancies complicated by CHB with different outcomes. Despite preventive treatment with hydroxychloroquine (HCQ) from 6 weeks of pregnancy onward, the fetus developed second to third degree CHB. Dexamethasone was added. The pregnancy evolved to near-term with persistent intermittent CHB. It is not clear how pregnancies with recurrent fetal CHB despite prophylaxis with HCQ should be managed and there is a need for controlled studies to answer the remaining questions in relation to this subject.