Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study.
BACKGROUND
Anti-SSA/Ro-associated third-degree congenital heart block is irreversible, prompting a search for early markers and effective therapy.


RESULTS
One hundred twenty-seven pregnant women with anti-SSA/Ro antibodies were enrolled; 95 completed an evaluable course in 98 pregnancies. The protocol included fetal echocardiograms performed weekly from 16 to 26 weeks' gestation and biweekly from 26 to 34 weeks. PR intervals >150 ms were considered prolonged, consistent with first-degree block. Ninety-two fetuses had normal PR intervals. Neonatal lupus developed in 10 cases; 4 were neonatal lupus rash only. Three fetuses had third-degree block; none had a preceding abnormal PR interval, although in 2 fetuses >1 week elapsed between echocardiographic evaluations. Tricuspid regurgitation preceded third-degree block in 1 fetus, and an atrial echodensity preceded block in a second. Two fetuses had PR intervals >150 ms. Both were detected at or before 22 weeks, and each reversed within 1 week with 4 mg dexamethasone. The ECG of 1 additional newborn revealed a prolonged PR interval persistent at 3 years despite normal intervals throughout gestation. No first-degree block developed after a normal ECG at birth. Heart block occurred in 3 of 16 pregnancies (19%) in mothers with a previous child with congenital heart block and in 3 of 74 pregnancies (4%) in mothers without a previous child with congenital heart block or rash (P=0.067).


CONCLUSIONS
Prolongation of the PR interval was uncommon and did not precede more advanced block. There was a trend toward more congenital heart block in fetuses of women with previously affected offspring than those without previously affected offspring. Advanced block and cardiomyopathy can occur within 1 week of a normal echocardiogram without initial first-degree block. Echodensities and moderate/severe tricuspid regurgitation merit attention as early signs of injury.
Friedman
Deborah M
DM
Department of Pediatrics, Saint Barnabas Medical Center, Livingston, NJ, USA.
Kim
Mimi Y
MY
Copel
Joshua A
JA
Davis
Claudine
C
Phoon
Colin K L
CK
Glickstein
Julie S
JS
Buyon
Jill P
JP
D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood; D003907:Dexamethasone; D004562:Electrocardiography; D005260:Female; D006327:Heart Block / Q000151:congenital / Q000175:diagnosis* / Q000276:immunology; D006330:Heart Defects, Congenital / Q000175:diagnosis* / Q000276:immunology; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000379:methods*
D000974:Antibodies, Antinuclear; C035356:SS-A antibodies; D003907:Dexamethasone