234: NAFTNET retrospective report on dexamethasone and fetal heart block

Complete atrioventricular block (CAVB) occurs in 1-2% of SSA positive pregnancies and the consequences are significant: approximately 20% die and 50% require permanent cardiac pacing by 1 year of age. We hypothesize that dexamethasone (DEX) treatment for fetal anti-SSA/SSB antibody-mediated cardiac disease leads to better pregnancy outcome. Therefore, we assessed recent era experience of treatment with DEX of pregnancies with SSA/SSB-mediated fetal cardiac disease including all degrees of heart block on pregnancy, neonatal outcome and complication rates. We performed a retrospective multi-center cohort study of all SSA/SSB antibody positive pregnancies with fetal conduction system disease reported to the participating NAFTNet centers between January 2010 through December 2017. The primary outcomes included preterm delivery, maternal comorbidities, neonatal complications and secondary outcomes were, need for a pacemaker < 28 days, heart transplantation in the 1st year of life, and intrauterine or neonatal death in maternal/fetal days treated with DEX versus managed expectantly. There was a total of 101 SSA/SSB positive pregnancies of which 75 were treated with DEX and 26 were not. Of those treated, 49/75 (65%) met the primary outcome including 37 premature deliveries; 12 mothers developed comorbidities during treatment (4 with fetal growth restriction, 4 with oligohydramnios, 2 with new or worsening gestational diabetes, and 6 with mood disturbances). In comparison, in the untreated group 11/26 (42%) met the primary outcome of premature delivery. Regarding secondary outcomes, 32/75 (43%) dexamethasone-treated fetuses either required a pacemaker or had a fetal demise/died by 28 days of life, while 13/26 (50%) untreated met the secondary outcome of requiring pacemaker placement or fetal demise/dying prior to 28 days of life, while 1 infant required listing for cardiac transplantation. While the use of dexamethasone in SSA and SSB positive pregnancies is associated with a high rate of poor pregnancy outcomes, there was a similarly high rate in untreated SSA/SSB positive pregnancies suggesting that the maternal disease itself is influencing pregnancy complications. A trend suggesting that treatment decreases neonatal morbidity and progression of conduction disease deserves further study.