The phenomenon of double interatrial septum (DIAS) represents a particularly rare subtype of atrial septal malformation, characterized by the presence of dual membranes separating the atria, resulting in a distinctive interatrial space. This unique anatomical structure has been linked to a paradoxical right–to-left shunt, potentially contributing to embolic ischemic strokes. Within this context, we report a rare case of a 34-year-old female who presented with a transient ischemic attack (TIA) and was diagnosed with patent foramen ovale (PFO) and a small adjacent atrial septal defect (ASD), along with the presence of a double interatrial septum. The diagnosis was confirmed wit transoesophageal echocardiography and cardiac MRI, and the condition was successfully treated with a transcatheter occluder device.

Keywords: Double interatrial septum; Patent foramen ovale; Ischemic stroke; Transcatheter occlusion; Atrial septal defect