Letter by Marijon Regarding Article, “Perinatal Outcome of Fetal Atrioventricular Block: One-Hundred Sixteen Cases From a Single Institution”
To the Editor:
I read with great interest the article of Lopes and colleagues on the perinatal outcome of fetal atrioventricular (AV) block.1 The authors readdressed the poor prognosis of fetal AV block when associated with structural heart disease, compared with fetuses that developed AV block without any associated structural heart disease (also called isolated fetal AV block).2 With regard to AV block not associated with structural heart disease, the authors reported that sero-negative fetuses had a similar prognosis to seropositive fetuses.
Recently, we reported from a monocentric experience (Necker Hospital, Paris, France) that 16 out of 56 children born with antibody-associated AV block (29%) developed dilated cardiomyopathy (DCM) during a mean follow-up of 9 years; DCM was diagnosed in fetal life or at birth in 10 subjects and during follow-up in the remaining 6 children.3 Six of the 56 children (11%) died during follow-up, all from progressive heart failure. In contrast, among 55 children born with isolated AV block and no evidence of any association with anti-Ro/anti-LA antibodies, no DCM was diagnosed and no deaths occurred during long-term follow-up. This adds further evidence to suggest that children with antibody-associated AV block have myocardial damage caused by the inflammatory process, which may progress or be reactivated during follow-up.3 However, pacemaker-induced DCM has been suggested to be a possible pathogenic factor because right ventricular pacing induces myocardial dystrophic changes.4 This seems unlikely in our series because the majority of paced children did not develop DCM, and most patients with DCM developed it before being paced.3
In the study of Lopes and al. however, 2 cases of delayed DCM were reported among 29 children (7%) with antibody-associated fetal AV block who survived the fetal and neonatal period. None of the children with fetal AV block without maternal antibodies developed DCM. Although their study included all children with AV block since the fetal period and provided important data on the impact of steroid therapy, it is possible that the authors underestimated the prognostic significance of the association with antibodies because they focused on “perinatal outcome of fetal AV block” or used inadequate DCM diagnostic criteria.
Finally, in addition to structural heart disease, considering antibody status in association with isolated fetal AV block is of great importance to better assess the long-term prognosis of such AV blocks.
Lopes LM, Tavares GM, Damiano AP, Lopes MA, Aiello VD, Schultz R, Zugaib M. Perinatal outcome of fetal atrioventricular block: one-hundred-sixteen cases from a single institution. Circulation. 2008; 118: 1268–1275.
Thambo JB, Bordachar P, Garrigue S, Lafitte S, Sanders P, Reuter S, Girardot R, Crepin D, Reant P, Roudaut R, Jaïs P, Haïssaguerre M, Clementy J, Jimenez M. Detrimental ventricular remodeling in patients with congenital complete heart block and chronic right ventricular apical pacing. Circulation. 2004; 110: 3766–3772.