Letter by Guettrot-Imbert et al Regarding Article, “Early Diagnosis and Treatment of Atrioventricular Block in the Fetus Exposed to Maternal Anti-SSA/Ro-SSB/La Antibodies”
To the Editor:
We read with great interest the article by Rein et al1 that describes how fetal kinetocardiogram can accurately detect first-degree congenital heart block (CHB) in fetuses exposed to maternal anti-SSA/Ro and/or anti-SSB/La antibodies. We question, however, whether these cases of first-degree CHB were all necessarily pathological and consequently in need of treatment.
The incidence of the first-degree CHB was 9% (6 affected fetuses among 70), which is much higher than the prevalence of 1% or 2% for complete and incomplete CHB found in a large series of infants born to mothers with these antibodies.2,3 Sonesson et al,4 who also found a high incidence of in utero first-degree CHB (33%), observed that most of the fetuses had spontaneous normalization of atrioventricular time intervals before birth or normal electrocardiograms shortly after birth without any treatment. It is thus likely that most of the neonates in the study by Rein et al1 would have had normal electrocardiograms without any in utero treatment.
As the authors of the PR Interval and Dexamethasone Evaluation (PRIDE) study5 emphasized, the clinical significance of a prolonged fetal PR interval is unclear because it may be spontaneously reversible, related to vagal tone, maternal medication use, or reversible injury. Because their mothers’ diseases and medications may affect fetuses, especially their atrioventricular conduction, a control group must be carefully defined and should include pregnant patients with connective tissue diseases but without anti-SSA or anti-SSB antibodies. Additionally, the analysis should be blinded.
These issues are important because overestimating the risk of CHB leads to fetuses being treated unnecessarily with a remedy that may have important side effects. The cumulative dose used is much higher than that used in the treatment of prematurity. As previous articles show, dexamethasone and betamethasone may be associated with oligoamnios, severe in utero growth restriction, prematurity, and stillbirth, all adverse obstetric outcomes similar to those observed in Cushing syndrome.2,5
Finally, the authors emphasized that the acquisition time for the PR was short. Nonetheless, an M-mode echocardiogram must still be performed to detect other possibly isolated cardiac manifestations related to anti-SSA/Ro antibodies, such as endocardial fibroelastosis and cardiac malformations.2
Rein AJ, Mevorach D, Perles Z, Gavri S, Nadjari M, Nir A, Elchalal U. 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. Circulation. 2009; 119: 1867–1872.
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.
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.