Long-Term Tvi-Based Study for Detection and Prevention of Complete Atrioventricular Bloc in Fetuses Exposed to Autoimmune Antibodies: Dexamethasone Prevents Deterioration of Low-Grade AV Block

Background

Fetuses to mothers positive for anti-SSA/Ro and/or Anti-SSB/La antibodies, may develop high grade atrioventricular (AV) block (AVB) with significant morbidity and mortality. Since 1999, we have implemented a single center program directed at detection of low-grade AVB by tissue velocity based fetal kinetocardiogram, and treated them with maternal oral fluorinated steroids in order to prevent the development of higher degree AVB. We hereby present the long-term follow-up (F/U), expanding our previously reported cohort (2009).

Methods and Results

310 fetuses at risk for AVB were referred to our center (1999-2016). They underwent serial fetal echocardiograms using tissue velocity imaging (TVI) methods. Mothers presented between 13 and 21 (mean 18) weeks of gestation for weekly evaluation up to week 26 with subsequent monthly F/U until labor. 288 fetuses (93%) retained normal AV conduction (NAVC) throughout gestation. 19 fetuses (6%) developed 1^st degree AVB. All reverted to NAVC after initiation of dexamethasone 4mg per day PO. One fetus had been referred with 2^nd AVB. He reverted to NAVC with dexamethasone. There was one unexpected IUFD. All living fetuses (309/310) were born with NAVC. Long-term F/U (1-15, mean 7.1 y) of the dexamethasone-treated children showed NAVC.

Conclusions

In this long-term F/U cohort of high-risk fetuses for CAVB, we reported the largest group of fetuses (20) with low-grade AVB (6%). All reverted to NAVC shortly after dexamethasone initiation. This supports our previous small preliminary study and confirms that TVI-based AV conduction measurement is adequate and that deterioration of low-grade AVB could be prevented by dexamethasone therapy.