Anti-SSA/Ro and anti-SSB/La antibody-mediated congenital heart block.

When anti-SSA/Ro antibodies are present in sera of mothers with connective tissue diseases, the incidence of congenital heart block (CHB) has been reported to be 1-2% in live births. The risk of recurrence of CHB in a subsequent child remains limited to 10-16%. CHBs are usually complete but CHB of the first or second degree can also be observed. In some cases, CHB is associated with endocardial fibroelastosis. Late-onset cardiomyopathy may occur later in life in these children. The mortality of CHB, which is predominant in utero and in the first months of life, is an estimated 16-19%. A pacemaker is required in about 66% of cases. Curative treatment of CHB is based on fluorinated steroids (dexamethasone or betamethasone) that do cross the placenta in an active form. Guidelines are available but further studies are needed to optimize treatment.