Prospective Evaluation of High Titer Autoantibodies and Fetal Home Monitoring in the Detection of Atrioventricular Block Among Anti-SSA/Ro Pregnancies

OBJECTIVE

This prospective study of pregnant patients, Surveillance To Prevent AV Block Likely to Occur Quickly (STOP BLOQ), addresses the impact of anti-SSA/Ro titers and utility of ambulatory monitoring in the detection of fetal second-degree atrioventricular block (AVB).

METHODS

Women with anti-SSA/Ro autoantibodies by commercial testing were stratified into high and low anti-52-kD and/or 60-kD SSA/Ro titers applying at-risk thresholds defined by previous evaluation of AVB pregnancies. The high-titer group performed fetal heart rate and rhythm monitoring (FHRM) thrice daily and weekly/biweekly echocardiography from 17-26 weeks. Abnormal FHRM prompted urgent echocardiography to identify AVB.

RESULTS

Anti-52-kD and/or 60-kD SSA/Ro met thresholds for monitoring in 261 of 413 participants (63%); for those, AVB frequency was 3.8%. No cases occurred with low titers. The incidence of AVB increased with higher levels, reaching 7.7% for those in the top quartile for anti-60-kD SSA/Ro, which increased to 27.3% in those with a previous child who had AVB. Based on levels from 15 participants with paired samples from both an AVB and a non-AVB pregnancy, healthy pregnancies were not explained by decreased titers. FHRM was considered abnormal in 45 of 30,920 recordings, 10 confirmed AVB by urgent echocardiogram, 7 being second-degree AVB, all <12 hours from normal FHRM and within another 0.75 to 4 hours to echocardiogram. The one participant with second/third-degree and two participants with third-degree AVB were diagnosed by urgent echocardiogram >17 to 72 hours from an FHRM. Surveillance echocardiograms detected no AVB when the preceding interval FHRM recordings were normal.

CONCLUSION

High-titer antibodies are associated with an increased incidence of AVB. Anti-SSA/Ro titers remain stable over time and do not explain the discordant recurrence rates, suggesting that other factors are required. Fetal heart rate and rhythm (FHRM) with results confirmed by a pediatric cardiologist reliably detects conduction abnormalities, which may reduce the need for serial echocardiograms.

Congenital diaphragmatic hernia in Smith-Magenis syndrome: a possible locus at chromosome 17p11.2

We report on a 7-month-old girl with Smith-Magenis syndrome (SMS) due to a 4.76-Mb deletion of 17p12-17p11.2 detected by array comparative genomic hybridization. She was also affected with a left-sided congenital diaphragmatic hernia (CDH) and cardiac anomalies including an atypical atrioventricular canal defect and a cleft mitral valve. To our knowledge, this is the first reported case of a patient with both SMS and CDH. There are numerous chromosomal regions in which duplications, deletions, inversions, or translocations have been associated with CDH, but none have previously been reported at or close to 17p11.2. We discuss candidate genes for the diaphragmatic defect in this patient. Our case demonstrates that it is important to consider the possibility of SMS in non-isolated cases of diaphragmatic hernia.