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Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La Background: An estimated 2-3% of pregnant women carry anti-Ro (anti-SSA) antibodies; complete AV block will develop in approximately 1-3% of the offspring of antibody-positive women. The odds of developing fetal heart block increase when there is a history of a prior sibling with complete AV block (17-18%), maternal hypothyroidism (18%), and (based on a single study) in mothers with high anti-Ro antibody titers. Anti-LA (anti-SSB) antibodies have not been associated in isolation with cardiac manifestions, but are believed by some to potentiate SSA antibody disease. Anti- Ro antibodies are particularly common in mothers with Sjogren’s syndrome (60-70% carry the anti-Ro Ab). Cardiac manifestions in the fetus in anti-Ro positive pregnancies most commonly include complete AV block, but can also include structural heart disease (~3%), valvular regurgitation, endocardial fibroelastosis (EFE), myocardial dysfunction, and lesser degrees of AV block (including 1st and 2nd degree), some of which progress to higher degree heart block(1). Although complete AV block is felt to be irreversible, there are case reports in the literature of resolution of 1st and/or 2nd degree AV block after treatment with dexamethasone. This has led to a impetus to screen anti-Ro positive pregnancies for the development of AV conduction abnormality, in an effort to identify lesser degrees of AV block (prior to development of complete AV block) that may be responsive to steroid treatment. Screening protocols: A number of screening protocols have been described in the literature(2, 3), outlining suggested intervals for assessment of fetal conduction and cardiovascular status in pregnancies complicated by maternal anti-Ro antibodies. It seems reasonable that the following protocols be applied: STANDARD RISK PROTOCOL: For anti-Ro positive pregnancies with no prior history of a child with complete AV block: Fetal echocardiography every 2 weeks between 16 and 26 weeks EGA, and once at 32 weeks EGA (if prior studies negative) Screening for structural cardiac anomalies on initial fetal echocardiogram For each fetal echo study, screening for the following findings will be performed: o AV conduction delay (i.e., first degree AV block), measured as the mechanical PR interval (as outlined below)
Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La o 2nd or 3rd degree AV block o Endocardial fibroelastosis o Pathologic valve regurgitation o Myocardial dysfunction Consideration for a trial of treatment with dexamethasone will be discussed with perinatalogist for findings of: o 1st degree AV block, where mechanical PR interval is > 150 msec (3 SD above normal) o Suspected 2nd degree AV block o Development of EFE, pathologic valve regurgitation, or myocardial dysfunction in the absence (or presence) of 1st or 2nd degree block Would strongly recommend referral to Egleston for confirmatory echocardiography if any of the above are suspected Recommend postnatal ECG to assess cardiac rhythm and conduction HIGH RISK PROTOCOL: For anti-Ro positive pregnancies with a positive prior history of a child with complete AV block: Fetal echocardiography every 1 week between 16 and 26 weeks EGA, and every 2 weeks between 26 and 32 weeks EGA (if prior studies negative) Screening for structural cardiac anomalies on initial fetal echocardiogram For each fetal echo study, screening for the following findings will be performed: o AV conduction delay (i.e., first degree AV block), measured as the mechanical PR interval (as outlined below) o 2nd or 3rd degree AV block o Endocardial fibroelastosis o Pathologic valve regurgitation o Myocardial dysfunction Consideration for a trial of treatment with dexamethasone will be discussed with perinatalogist for findings of: o 1st degree AV block, where mechanical PR interval is > 150 msec (3 SD above normal) o Suspected 2nd degree AV block o Development of EFE, pathologic valve regurgitation, or myocardial dysfunction in the absence (or presence) of 1st or 2nd degree block
Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La Would strongly recommend referral to Egleston for confirmatory echocardiography if any of the above are suspected Recommend postnatal ECG to assess cardiac rhythm and conduction Would recommend conversion to HIGH RISK PROTOCOL for: Cases where mechanical PR interval is > 140 msec (prolonged, > 2 SD above normal), but not > 150 msec (3 SD above normal)
Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La Figure 1: PW Doppler sample of LV inflow-outflow for measurement of mechanical PR interval(4). Interval is measured from the notch in the E-A complex to the beginning of LV outflow (per below)
Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La Figure 2. PW Doppler simultaneous sample of ascending aorta (Ao) and SVC flow for measurement of mechanical PR interval(4). The SVC S and D waves are noted; the atrial systolic reversal in indicated by red/white arrows. The PR interval is measured from the onset of the SVC A-wave to the onset of aortic (Ao) flow.
Fetal Screening in Mothers with Positive Autoantibodies for Anti-Ro, Anti-La REFERENCES: 1. Sonesson SE, Salomonsson S, Jacobsson LA, Bremme K, Wahren-Herlenius M. Signs of first-degree heart block occur in one-third of fetuses of pregnant women with anti-SSA/Ro 52- kd antibodies. Arthritis Rheum. 2004;50(4):1253-61. 2. Friedman DM, Kim MY, Copel JA, Davis C, Phoon CK, Glickstein JS, et al. Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study. Circulation. 2008;117(4):485-93. 3. Jaeggi ET, Silverman ED, Laskin C, Kingdom J, Golding F, Weber R. Prolongation of the atrioventricular conduction in fetuses exposed to maternal anti-Ro/SSA and anti-La/SSB antibodies did not predict progressive heart block. A prospective observational study on the effects of maternal antibodies on 165 fetuses. J Am Coll Cardiol. 2011;57(13):1487-92. 4. Andelfinger G, Fouron JC, Sonesson SE, Proulx F. Reference values for time intervals between atrial and ventricular contractions of the fetal heart measured by two Doppler techniques. Am J Cardiol. 2001;88(12):1433-6, A8.