Transplacentar transfer of maternal anti-Ro and/or anti-La autoantibodies may result in cardiac disease such as heart block and cardiomyopathy. Complete congenital heart block is a rare but devastating condition of cardiac Neonatal Lupus and may result in heart failure and foetal death.
Complete atrioventricular block is considered to be irreversible. It seems that maternal anti-Ro levels ant presence of anti-Ro52 component predict fetuses at high risk of immune-mediated cardiac complications.
Maternally administered corticosteroids may limit the progression of the 1st or the 2nd atrioventricular block. However, the transition from normal sinus rhythm to the third-degree atrioventricular rhythm may be rapid (< 24 hours).
Dexamethasone given during pregnancy may achieve normalization of prolonged atrioventricular conduction time interval and averts the progression to complete heart block, often used in combination with intravenous immunoglobulin administration. In fetuses with complete AV block, the effect of steroid treatment on outcome is not proven.
Hydroxychloroquine treatment during preganancy has been associated with a decreased recurrence of cardiac Neonatal Lupus.