Incidence, risk factors, and mortality of neonatal and late-onset dilated cardiomyopathy associated with cardiac neonatal lupus.

Background: Dilated cardiomyopathy (DCM), a well-known complication of cardiac neonatal lupus, is associated with high mortality rate. Its risk factors remain unclear.

Methods: We analyzed occurrence of postnatal DCM among children with high-degree congenital heart block (CHB) and mothers with anti-SSA and/or anti-SSB antibodies.

Results: Among 187 neonates with CHB, 35 (18.8%, one missing data) had DCM and 22 (11.8%) died during a median follow-up of 7years [range: birth-36years]. On multivariate analysis, factors associated with postnatal DCM were in utero DCM (P=0.0199; HR=3.13 [95% CI: 1.20-8.16]), non-European origin (P=0.0052; HR=4.10 [95% CI: 1.81-9.28]) and pacemaker implantation (P=0.0013; HR=5.48 [95% CI: 1.94-15.47]). Postnatal DCM could be categorized in two subgroups: neonatal DCM (n=13, diagnosed at a median age of 0day [birth-4days]) and late-onset DCM (n=22, diagnosed at a median age of 15.2months [3.6months-22.8years]). Factors associated with neonatal DCM were in utero DCM, hydrops, endocardial fibroelastosis and pericardial effusion, whereas those associated with late-onset DCM were non-European origin, in utero mitral valve insufficiency, and pacemaker implantation. Fluorinated steroids showed no protective effect against late-onset DCM (P=0.27; HR=1.65 [95% CI: 0.63-4.25]). Probability of survival at 10years was 23.1% for newborns diagnosed neonatally with DCM, 53.9% for those who developed late-onset DCM, and 98.6% for those without DCM.

Conclusion: Neonatal and late-onset DCM appear to be two different entities. None of the known risk factors associated with neonatal DCM predicted late-onset DCM. Long-term follow-up of cardiac function is warranted in all children with CHB.