Absence of conduction defects in the echocardiograms of mothers with children with congenital complete heart block

Objective. To investigate the association between complete congenital heart block (CCHB) in the fetus and adult disease. Methods. We prospectively studied 111 consecutive patients with systemic lupus erythematosus (SLE) or a positive extractable nuclear antigen (Ro, La, or RNP) attending a connective tissue disease (CTD) clinic and 19 patients who had had children with CCHB. Electrocardiographs were recorded on all patients and subsequently analyzed blindly. Results. There was a significantly shorter PR interval in the mothers of children with CCHB compared to patients attending the CTD clinic (p < 0.02). There was no significant difference in PR interval between Ro positive and Ro negative patients in the CTD clinic. There were no significant differences in QRS or QTc duration between mothers with CCHB children and Ro positive or Ro negative patients attending the CTD clinic, The shorter PR interval in the mothers with CCHB children may be explained by their significantly younger age compared to patients in the CTD clinic (p < 0.02, 95% CI) and the lower incidence of CTD. Conclusion. We were unable to confirm the association between anti-Ro antibodies and cardiac conduction defects in adults. This supports theories that CCHB is due to vulnerability peculiar to the fetal heart during a particular stage of development between 16 and 30 weeks of gestation.