Clinical and serological identification of 2 forms of complete heart block in children.

OBJECTIVE

To study the association of maternal antibodies to Ro(SSA) and/or La(SSB) with isolated complete congenital heart block (CCHB) in children according to the child's age at detection.

METHODS

Sera from 17 mothers of 18 children with CCHB of unidentified cause were studied. Autoantibodies were measured by double immunodiffusion, enzyme linked immunosorbent assay (ELISA), Western blot, and immunoprecipitation from cell extracts. Statistical analysis used the chi 2 test with Yates' correction.

RESULTS

CCHB was diagnosed in 12 children of 11 mothers before the age of 3 mo (Group A) and in 6 children of 6 mothers after the age of 17 mo (Group B). Seven Group A mothers and no Group B mother had connective tissue disorders; autoantibodies were found in 9/11 Group A and in 1/6 Group B mothers (p < 0.01). Eight Group A children needed a pacemaker and one other died of cardiac insufficiency, whereas only one of the 6 Group B children needed a pacemaker. Interestingly, this latter child was the only one from Group B whose mother's serum contained autoantibodies. Irrespective of their age at diagnosis, the children with CCHB who needed a pacemaker and the one who died were born to mothers with autoantibodies (p < 0.001).

CONCLUSION

CCHB detected before the age of 3 mo is highly associated with the presence of anti-Ro(SSA)/La(SSB) in the mothers, while CCHB diagnosed later is generally not. For epidemiological studies, the former type should be considered early onset as opposed to late onset CCHB in the latter type. Establishing this clinicoserological distinction is also important for the children, since it alerts the clinician to a more severe prognosis (necessity of a pacemaker), even in the rare occurrence of late diagnosed CCHB.