Objective: To determine the initial clinical status and the long-term outcome of mothers and their children with autoantibody-associated congenital heart block.

Design: Dynamic, longitudinal cohort study.

Patients: 55 children with isolated congenital heart block, their 52 mothers, and 5 other women currently carrying fetuses with congenital heart block. All maternal sera contained antibodies to SSA/Ro alone or to both SSA/Ro and SSB/La.

Measurements: Clinical information obtained from mailed questionnaires, telephone interviews, primary physicians, and chart reviews.

Results: When congenital heart block was identified in the children, 23 women were asymptomatic, 15 had systemic lupus erythematosus, 8 had the Sjögren syndrome, and 11 had an undifferentiated autoimmune syndrome. Follow-up ranged from 1 week to 20 years (median, 3.7 years). Eleven (48%) of the 23 initially asymptomatic mothers developed symptoms of a rheumatic disease (0.15 status changes/patient-year of follow-up; 6 (26%) developed an undifferentiated autoimmune syndrome, 2 (9%) developed the Sjögren syndrome, and 3 (13%) developed systemic lupus erythematosus. One mother with the Sjögren syndrome progressed to systemic lupus erythematosus. Four (16%) of 25 subsequent pregnancies in 22 women were complicated by heart block. Seventeen affected children died, 12 within 1 month of birth. Pacemakers were implanted in 37 (67%) of the 55 children, 27 within 3 months after birth.

Conclusion: The development of rheumatic disease in asymptomatic mothers identified by the birth of a child with congenital heart block is common but not universal. The risk for congenital heart block in subsequent pregnancies is low. One third of the children with autoantibody-associated congenital heart block die in the early neonatal period and, of those who survive, most require pacemakers.