Abstract 9355: Home Monitoring to Detect Emergent Anti-Ro/SSA Antibody Mediated Fetal Av Block: Preliminary Results of the STOP BLOQ Study

Abstract

Introduction: Fetal complete AV block (CAVB), complicates 2% of anti-Ro antibody positive pregnancies and carries substantial perinatal morbidity and mortality. Anti-inflammatory treatment of 1° and 2° (emergent) AVB may prevent progression to CAVB, yet the optimal surveillance strategy to detect emergent CAVB is unknown. Methods: We examined participants in a multicenter, open label clinical trial of pregnancies risk stratified by anti-Ro antibodies into high (≥1000 IU) or low (<1000 IU) titers. Low titer mothers were followed by echocardiograms or routine OB care; high titer mothers underwent 3x/day fetal heart rate monitoring (FHRM) and weekly or biweekly fetal echocardiograms from 17-26 weeks. If mothers suspected abnormal FHRM, they texted fetal heart sounds to cardiologist, who assessed FHRM and reassured or referred for emergency fetal echocardiogram (performed in < 6 hours). Postnatal electrocardiograms (ECG) were evaluated. Results: Sixty-five subjects from 7 centers were recruited and 60 (92%) enrolled at 14 (5-19) weeks. There were 24 (40%) low titer and 36 (60%) high titer mothers. High titer mothers underwent FHRM; 92% completed FHRM and 100% completed surveillance echocardiograms. Of 3,360 FHRM recordings, mothers texted 39 (1%) recordings of concern; cardiologist deemed 2/39 (5%) as abnormal and emergency echocardiograms revealed atrial ectopy. No fetus developed emergent or CAVB. Postnatal ECGs demonstrated normal AV conduction in all neonates: 2 miscarried at <12 weeks and 48 are in utero. Conclusion: These data support FHRM in the surveillance of anti-Ro antibody positive pregnancies because of high enrollment, feasibility, and accuracy in arrhythmia detection.