In search of an antibody specificity highly predictive of congenital heart block

Autoimmune Calcium Channelopathies and Cardiac Electrical Abnormalities

Patients with autoimmune diseases are at increased risk for developing cardiovascular diseases, and abnormal electrocardiographic findings are common. Voltage-gated calcium channels play a major role in the cardiovascular system and regulate cardiac excitability and contractility. Particularly, by virtue of their localization and expression in the heart, calcium channels modulate pace making at the sinus node, conduction at the atrioventricular node and cardiac repolarization in the working myocardium. Consequently, emerging evidence suggests that calcium channels are targets to autoantibodies in autoimmune diseases. Autoimmune-associated cardiac calcium channelopathies have been recognized in both sinus node dysfunction atrioventricular block in patients positive for anti-Ro/La antibodies, and ventricular arrhythmias in patients with dilated cardiomyopathy. In this review, we discuss mechanisms of autoimmune-associated calcium channelopathies and their relationship with the development of cardiac electrical abnormalities.

Prenatal heart block screening in mothers with SSA/SSB autoantibodies: Targeted screening protocol is a cost-effective strategy

OBJECTIVE

Maternal anti-Ro/SSA and anti-La/SSB antibodies can lead to fetal complete heart block (CHB). Current guidelines recommend weekly echocardiographic screening between 16 and 28 weeks gestation. Given the cost of screening and the rarity of conduction abnormalities in fetuses of mothers with low anti-Ro levels (<50 U/mL), we sought to identify a strategy that optimizes resource utilization.

DESIGN

Decision analysis cost-utility modeling was performed for three screening paradigms: "standard screening" (SS) in which mid-gestation mothers are screened weekly, "limited screening" (LS) in which fetal echocardiograms are avoided unless the fetus develops bradycardia, and "targeted screening by maternal antibody level" (TS) in which only high anti-Ro values warrant weekly screening. A systematic review of existing literature and institutional cost data were used to define model inputs.

RESULTS

The average cost of LS, TS, and SS was $8566, $11 038, and $23 279, respectively. SS was cost-ineffective with an incremental cost-effectiveness ratio (ICER) of $322 756 while TS was cost-effective with an ICER of $43 445.

CONCLUSION

While the efficacy of fetal intervention for first or second degree AV block remains unclear, this analysis supports utilizing antibody levels to stratify this population for optimized surveillance for CHB. SS is cost-ineffective and results in resource overutilization.

Progress in the pathogenesis and treatment of cardiac manifestations of neonatal lupus

PURPOSE OF REVIEW

To provide new insights into pathogenesis, prevention and management of cardiac manifestations of neonatal lupus (cardiac neonatal lupus) and issues pertinent to all anti-SSA/Ro positive individuals of childbearing age.

RECENT FINDINGS

Antibody specificity with high risk for cardiac neonatal lupus remains elusive, but high titers of Ro60, Ro52 or Ro52p200 antibodies appear to be required. Varying antibody specificities to the p200 region of Ro52 can induce first-degree block in a rodent model. In consideration of the contribution of macrophages to inflammation and fibrosis in cardiac neonatal lupus, hydroxychloroquine (HCQ) is being considered as preventive therapy. Cord blood biomarkers support the association of fetal reactive inflammatory and fibrotic components with the development and morbidity of cardiac neonatal lupus. Data from U.S. and French registries do not provide evidence that the prompt use of fluorinated steroids in cases of isolated block significantly alters fetal/neonatal morbidity or mortality.

SUMMARY

The search for a high-risk cardiac neonatal lupus antibody profile remains, but high-titer antibodies to Ro60 and R052 are a consistent finding, and this may guide the need for fetal echocardiographic surveillance. The uniform use of fluorinated steroids to prevent progression of cardiac neonatal lupus or reduce mortality does not appear justified. HCQ, based on diminishing an inflammatory component of cardiac neonatal lupus, is under consideration as a potential preventive approach.