Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study

Circulation. 2008 Jan 29;117(4):485-93. doi: 10.1161/CIRCULATIONAHA.107.707661. Epub 2008 Jan 14.


Background: Anti-SSA/Ro-associated third-degree congenital heart block is irreversible, prompting a search for early markers and effective therapy.

Methods and 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.

Trial registration: ClinicalTrials.gov NCT00007358.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Antibodies, Antinuclear / blood
  • Dexamethasone
  • Electrocardiography*
  • Female
  • Heart Block / congenital
  • Heart Block / diagnosis*
  • Heart Block / immunology
  • Heart Defects, Congenital / diagnosis*
  • Heart Defects, Congenital / immunology
  • Humans
  • Infant, Newborn
  • Male
  • Pregnancy
  • Prenatal Diagnosis / methods*


  • Antibodies, Antinuclear
  • SS-A antibodies
  • Dexamethasone

Associated data

  • ClinicalTrials.gov/NCT00007358