Prospective echocardiographic evaluation of AV conduction in fetuses with maternal SSA/SSB antibodies

Abstract

TION IN FETUSES WITH MATERNAL SSA/SSB ANTIBODIES ANDREW VAN BERGEN, MARC OVADIA, RONALD WAKAI, BRIAN MCCULLOCH, MARK KALCHBRENNER, BETTINA CUNEO, The Heart Institute for Children, Perinatal Cardiology, Oak Lawn, IL The University of Wisconsin, Medical Physics, Madison, WI Advocate Perinatal Center, Maternal Fetal Medicine, Park Ridge, IL Advocate Perinatal Center, Maternal Fetal Medicine, Oak Lawn, IL OBJECTIVE: While only a small fraction of SSA/SSB-positive pregnancies are complicated by complete heart block (HB), substantial fetal and infant morbidity andmortality, as well as reports of successful treatment of incomplete HB with maternally administered steroids, make early diagnosis of conduction abnormalities desirable. In this study we investigated whether prospective Doppler interrogation of the mechanical PR interval could identify fetuses with incomplete HB who might benefit from in utero treatment. STUDY DESIGN: Maternal histories and fetal echocardiograms performed secondary to maternal SSA/SSB antibodies at two large maternity services between 1997 and 2003 were reviewed. The mechanical PR interval .was measured from onset of mitral A wave to onset of aortic outflow for three beats. The mean ( ± SD) mechanical PR intervals of study patients were compared to fetuses with known autoimmune firstand second-degree HB on fetal magnetocardiography (controls). Differences were determined by MannWhitney test. RESULTS: 128 fetal echocardiograms were performed on 68 women at 23.7 ± 5.1 (range 16-32 weeks) during their 1st (36), 2nd (18), 1st and 2nd (4), or >2nd (10) pregnancies. One previous child had incomplete fetal HB that did not progress after maternally administered dexamethasone. Sixty-four mothers had SSA, and 4 had SSA/SSB antibodies. Mechanical PR intervals ranged from 97-142 (121.3 ± 11.8) msec in the study group and were significantly different from the 4 controls (191.5 ± 22.4msec, P = 000). All study infants were liveborn with no HB or dilated cardiomyopathy. CONCLUSION: Mechanical PR intervals can be successfully measured in fetuses from 16-32 weeks of gestation. The incidence of conduction abnormalities in fetuses with maternal SSA/SSB and a negative family history is extremely low (0/68). The mechanical PR is an effective discriminant and should be evaluated prospectively.