Response to Letter Regarding Article, “Early Diagnosis and Treatment of Atrioventricular Block in the Fetus Exposed to Maternal Anti-SSA/ Ro-SSB/La Antibodies: A Prospective, Observational, Fetal Kinetocardiogram-Based Study”
We thank Guettrot-Imbert et al for their comments. They question whether all cases of first-degree atrioventricular block (AVB) were necessarily pathological and in need of treatment. They also question our 8.6% incidence of first-degree AVB versus the 1% to 2% rate described elsewhere.
As emphasized in our article, our sole objective was to show the use of tissue velocity imaging–derived atrioventricular conduction measurement in this specific population, not to assess the efficacy of dexamethasone in anti-SSA/Ro- and/or anti-SSB/La-exposed fetuses. We agree that a blinded control study should be carefully designed for this purpose, although this goal is challenging given the rarity of the disease.1,3
Relative to our high incidence (6 of 70, 8.6%) of first-degree AVB, this number is not far from the 2% to 5% incidence reported by others. Moreover, reports of 2% to 5% incidence apply to third-degree AVB, whereas our 8.6% incidence addresses first-degree AVB, which might be much higher. It is logical to assume that some first-degree AVB might deteriorate rapidly to third degree2 and cause fetal demise, thus excluding them from the 2% to 5% incidence. Whether some first-degree AVB could revert spontaneously to normal conduction, as suggested, is debatable. In our experience of hundreds of atrioventricular conduction time measurements with tissue velocity imaging, we never encountered atrioventricular conduction of >106 ms in normal fetuses. Sonesson et al3 reported a 33% incidence of first-degree AVB with a significant level of spontaneous reversion. We previously attributed their high incidence to a questionable definition of first-degree AVB.4
Our small study group is also atypical and may not reflect a “low-normal” risk population of anti-SSA/Ro- and/or anti-SSB/La-exposed fetuses. One fetus with first-degree AVB (No. 3) had a previous sibling with third-degree AVB (risk of 25% for recurrence). Also, the mother of the twin fetuses (Nos. 1 and 2) suffered from mixed connective tissue disease and was childless, having lost 4 pregnancies, suggesting exposure and possible AVB. With these high-risk fetuses removed, the “statistics” would show first-degree AVB in 3 of 67 fetuses (4.5%), which is in the reported range.
We discussed the risk of dexamethasone treatment in the fetus and the mother, and one may question the justification of treatment with fluorinated steroids. However, we believe, as do others,2 that the risk for escalation toward high-grade AVB might outweigh the risks of treatment in this high-risk population. We agree that M-mode echocardiogram could be performed to detect other possibly isolated cardiac manifestations, such as endocardial fibroelastosis and cardiac malformations, but we did not examine this issue.
We call for a rheumatology–pediatric cardiology consensus declaration on this matter, and we suggest that a multicenter international collaboration of investigators, with a large cohort of exposed fetuses such as the cohort described by Costedoat-Chalumeau et al,5 be established to address the issue of dexamethasone therapy in this population.
Friedman DM, Kim MY, Copel JA, Davis C, Phoon CK, Glickstein JS, Buyon JP. Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study. Circulation. 2008; 117: 485–493.
Costedoat-Chalumeau N, Amoura Z, Lupoglazoff JM, Huong DL, Denjoy I, Vauthier D, Sebbouh D, Fain O, Georgin-Lavialle S, Ghillani P, Musset L, Wechsler B, Duhaut P, Piette JC. Outcome of pregnancies in patients with anti-SSA/Ro antibodies: a study of 165 pregnancies, with special focus on electrocardiographic variations in the children and comparison with a control group. Arthritis Rheum. 2004; 50: 3187–3194.