Isolated atrioventricular block of unknown origin in the adult and autoimmunity: diagnostic and therapeutic considerations exemplified by 3 anti-Ro/SSA–associated cases

A large body of evidence links the presence of circulating anti-Ro/SSA antibodies (anti-Ro/SSAs) in a mother with the risk of her newborn developing neonatal lupus, a paradigmatic model of transplacental passively acquired autoimmunity whose main cardiac manifestation is congenital complete atrioventricular block (congenital-III°AVB).1 Although the precise underlying mechanisms of the block have not been fully elucidated, many experimental studies have demonstrated the ability of anti-Ro/SSA to biochemically cross-react with L-type and T-type calcium channels and thus significantly inhibit the related currents, both of which play a key role in the slow action potential of the conduction system cardiomyocytes.