Background/Purpose:  Circulating anti-Ro/SSA antibodies may rarely affect the adult conduction-system. A direct autoantibody-mediated electrophysiological inhibition of cardiomyocyte calcium-channels (acquired form) or an ante-natal subclinical injury induced by maternally-acquired anti-Ro/SSA with an autoantibody-independent worsening with age until a late diagnosis in the adulthood (late progressive congenital form) are the putative mechanisms involved.

Methods: We collected three clinical cases that provide further evidences of this view. 

Results:

Case 1. A 29-years-old woman presented with chest pain and faintness. The ECG demonstrated the presence of  III° atrioventricular block (AVB). The clinical history was negative except for autoimmune thyroiditis and subclinical positivity for anti-Ro/SSA A pacemaker was implanted but after methylprednisolone 40 mg/daily normal AV conduction was restored.

 Case 2. A I°AVB with episodes of  II°AVB and high-grade AVB was discovered  in an asymptomatic 23-year-old woman who underwent routine screening. Her clinical history was negative. A previous ECG demonstrated that I°AVB was already present at 9 years of age. Anti-Ro/SSA were negative, but these antibodies were positive in the mother. A backup permanent pacemaker was implanted.

Case 3. A 21-year-old woman with autoimmune thyroiditis presented with III°AVB. The laboratory evaluation demonstrated a positive test for anti-Ro/SSA-52kD (immuno-Western blot), although FEIA testing was negative. Her mother was totally asymptomatic for connective tissue diseases (CTDs), but was found to be positive for anti-Ro/SSA-52kD (immuno-Western blot). Methylprednisolone 1 mg/Kg/day was initiated resulting in a rapid disappearance of III°AVB.  At the interruption of the therapy 3 months after there was the reoccurrence of complete AVB, and again methylprednisolone rapidly restored normal AV conduction. The opportunity of implanting a pace-maker is under consideration.

Conclusion: these 3 cases provide an exemplification of the different forms of anti-Ro/SSA-associated AVB in adults. The patient 1 and patient 2  represent respectively a case of acquired form and a case as a late progressive congenital form. Finally, the patient 3 may represent a mixed form, in which both the above mechanisms have been involved. In conclusion  a specific anti-Ro/SSA testing (ELISA + immuno-Western blot) in the patient and patient’s mother may be diagnostic in rare adults with unexplained AVB, also in the absence of signs of CTDs; if anti-Ro/SSA are present, a prompt immunomodulating therapy may induce a rapid reversion of this life-threatening rhythm disturbance, thus avoiding or delaying pacemaker implantation.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/isolated-atrioventricular-block-of-unknown-origin-in-the-adult-and-autoimmunity-diagnostic-and-therapeutic-considerations-exemplified-by-three-anti-rossa-associated-cases/