NEW YORK — High-dose steroid therapy only rarely lessened the degree of congenital heart block in one study of 30 affected pregnancies, according to Dr. Jill P. Buyon.
In a prospective, multicenter, observational study, 30 pregnancies involving a fetus with some degree of autoimmune-associated congenital heart block were treated with 4 mg/day of dexamethasone. In all, 22 of the fetuses had third-degree heart block, 6 had second-degree heart block, and 2 had first-degree heart block. Another 10 similar pregnancies that were not treated with dexamethasone served as the control group, in which nine fetuses had third-degree heart block and one had first-degree heart block. Initial median ventricular rates, age at diagnosis, and degree of cardiac dysfunction were similar between groups, said Dr. Buyon, professor of medicine at New York University.
Although this was initially intended to be a randomized, controlled trial, that plan was not feasible, so the decision to treat with dexamethasone was made by the managing physicians.
Six deaths occurred in the group that was treated with dexamethasone, and four deaths occurred in utero, one at 15 months post partum and the other at 2 years of age.
None of the 40 fetuses experienced a reversal of third-degree block, either with therapy or spontaneously. In fetuses who were treated with dexamethasone, one in six with second-degree block progressed to third-degree block, and three remained in second-degree block at birth. After birth, one child was given a pacemaker; two others progressed to third-degree block. At birth, two babies with second-degree heart block converted to normal sinus rhythm. While one maintained sinus rhythm, the other reverted to second-degree heart block. Of the two fetuses with first-degree heart block, both converted to normal sinus rhythm at birth and maintained it throughout follow-up (Am. J. Cardiol. 2009;103:1102–6).
Among the 10 fetuses in the control group, 9 with third-degree block in utero maintained it, and 1 with first-degree block converted to sinus rhythm, Dr. Buyon said at a rheumatology meeting sponsored by the university. These findings do not preclude ever using dexamethasone in such pregnancies, she said. Physicians who elect to use dexamethasone in affected pregnancies should stop the therapy if it proves ineffective, which can be ascertained using serial echocardiograms. Physicians need to remember that every case is individual and the guidelines may be of limited applicability.
A fetus who is found to have a third-degree block of more than 1 week's duration should be followed with weekly echocardiograms and obstetric ultrasound, but no therapy, she said. When the third-degree block is shorter than 1 week in duration, the baby should be given 4 mg of dexamethasone daily for 1-2 weeks. Therapy should be discontinued if the baby's condition does not improve. However, if the baby's heart block reverses to second degree or even milder, the treating physician should consider continuing daily dexamethasone for 4-6 weeks and continuing weekly echocardiograms.
Disclosures: Dr. Buyon said she had no relevant financial relationships to disclose except for support from the National Institute of Arthritis and Musculoskeletal and Skin Diseases, the American Heart Association, the Kirkland Center, the Alliance for Lupus Research, and a gift from the Lee family of Brooklyn, N.Y.