Atrioventricular Conduction Delay in Fetuses Exposed to Anti-SSA/Ro and Anti-SSB/La Antibodies: A Magnetocardiography Study

Abstract

Background. The presence of anti-SSA/Ro and anti-SSB/La antibodies during pregnancy is associated with fetal congenital heart block (CHB), which is primarily diagnosed through fetal echocardiography. Conclusive information about the complete electrophysiology of the fetal cardiac conducting system is still lacking. In addition to echocardiography, fetal magnetocardiography (fMCG) can be used. fMCG is the magnetic analogue of the fetal electrocardiogram (ECG). Patients and Methods. Forty-eight pregnant women were enrolled in an observational study; 16 of them tested positive for anti-SSA/Ro and anti-SSB/La antibodies. In addition to routine fetal echocardiography, fMCG was used. Fetal cardiac time intervals (fCTIs) were extracted from the magnetic recordings by predefined procedures. ECGs in the neonates of the study group were performed within the first month after delivery. Results. The PQ segment of the fCTI was significantly prolonged in the study group (P = 0.007), representing a delay of the electrical impulse in the atrioventricular (AV) node. Other fCTIs were within normal range. None of the anti-SSA/Ro and/or anti-SSB/La fetuses progressed to a more advanced heart block during pregnancy or after birth. Conclusion. The study identified a low-risk population within antibody positive mothers, where PQ segment prolongation is associated with a lack of progression of the disease.

The clinical spectrum of autoimmune congenital heart block

“…Other diagnostic tests (electrocardiogram plus Holter monitor, magnetocardiography, gated-pulsed Doppler technique, velocity-based fetal kinetocardiogram) might detect subtle signs of the development of CHB, but their use is not standard practice. 93–96 Serial echocardiograms and obstetric sonograms should be performed weekly from 16 weeks of gestation onwards, although the frequency might be reduced in the absence of CHB after week 26, as we found that <20% of cases are diagnosed after week 30 of gestation. Serial echocardiograms should also evaluate EFE, which might be subclinical, like type I CHB, but with a worse prognosis.…”

Fetal manifestations of maternal anti‐Ro and La antibodies – more than complete heart block

“…Whilst CHB is the most widely studied and recognised aspect of fetal exposure to anti‐Ro antibodies, there are numerous reports of complications beyond those illustrated in this report. These include sinus bradycardia 6 , first degree AV block 1 , 3 , second degree AV block 2 , atrial flutter 2 , tricuspid valve chordal rupture with severe tricuspid regurgitation 5 and dilated cardiomyopathy 4 , 7 …”

Autoimmune-associated Congenital Heart Block

“…It is urgently necessary to define the susceptible populations, from both maternal and fetal aspects. [ 2 15 26 27 28 29 30 31 32 33 34 35 36 37 ] The efficacy of current approaches for preventing the CHB progression in affected fetus and recurrence in subsequent pregnancy as well as other autoimmune-mediated damages is still controversial. The parameters to weigh out the risk and benefit remain to be determined.…”

“…While most of fetal CHB cases can be reliably diagnosed through fUCG, it fails to provide conclusive information regarding electrophysiology of the fetal cardiac conducting system. fMCG is the magnetic analog of the fetal electrocardiogram (fECG),[ 32 ] and fetal cardiac time intervals could be extracted from the fMCG recordings by predefined procedures. In addition, fMCG results may also be utilized to monitor disease progression.…”

“…Furthermore, recent studies showed that fMCG can be effectively used in the prenatal diagnosis of atrial bigeminy (conducted and blocked), 2:1 AVB, CAVB, delayed AV conduction, PQ segment prolongation, and different types of long QT syndrome. [ 32 33 34 35 ]…”