Is isolated congenital heart block associated to neonatal lupus requiring pacemaker a distinct cardiac syndrome?

Abstract

Isolated congenital heart block (ICHB) is frequently associated with neonatal lupus syndrome (NLS). Therefore few data are available regarding the long-term cardiac outcome of newborns with ICHB and the pathogenic mechanisms are not yet defined. In order to compare demographic features and cardiological outcome of patients with ICHB submitted to pacemaker (PM) implantation with and without NLS, forty ICHB patients were evaluated pre- and post-PM implantation, by clinical, electrocardiogram, Holter Monitoring, treadmill test, and electrophysiological study. According to the presence of antibodies to 52 and 60 kDa Ro/SSA and La/SSB proteins in mother's sera, it was found that 60% (24/40) of patients had ICHB associated to NLS (ICHB/NL+). Twenty-three of 24 ICHB/NL+ patients were asymptomatic, and 16 (67%) were female (P = 0.013). The frequency of syncope, mitral insufficiency (MI), and congestive heart failure (CHF) was similar pre-PM implantation in both ICHB/NL+ and ICHB/NL- groups (P > 0.05). After PM implantation, MI and CHF were only observed in ICHB/NL+ patients, although not statistically significant. Interestingly, 67% of ICHB/NL+ were noticed before one year of age while only one fourth of ICHB/NL- was diagnosed in this period (P = 0.024). Almost half (46%) of ICHB/NL+ patients required PMs in the first 24 months of life, whereas only one in the ICHB/NL- received a PM at the same age (P = 0.02). In ICHB patients requiring PM implantation, the antibody-mediated lesion seems to be associated with an earlier onset and a more severe heart disease, in spite of the uniform criteria for PM indication.