Fetal Atrial Flutter: A Potential Rare Phenotype of Maternal SSA/SSB Antibody–Associated Fetal Cardiac Disease

To the Editor:

Fetal atrial flutter (AF) is a reentrant tachyarrhythmia characterized by very fast, regular atrial and ventricular rates (400-500 bpm and 200-220 bpm, respectively). It occurs mainly in an anatomically normal heart and is usually treated with digoxin, which is often effective, with no further recurrence.¹

Maternal autoimmunity leading to transplacental SSA/SSB antibody passage may constitute a rare cause of AF. It is still unclear if extranodal atrial myocardial involvement is an isolated event in neonatal lupus erythematosus (NLE) or if it could precede the atrioventricular (AV) conduction system involvement.

We report the case of a 31-year-old woman presenting for a routine obstetric visit at 29 gestational weeks, during which fetal AF (2:1 transmission) was identified (Figure 1). Fetal structural and functional organ abnormalities were excluded. Maternal clinical examination and electrocardiogram were normal. Screening tests for infectious diseases and thyroid function, as well as drug intake history, were negative. Subsequently, screening tests for autoimmune diseases potentially linked to fetal heart pathology were completed.²