Atrial Septal Aneurysm & Stroke: Understanding the Risk

An atrial septal aneurysm (ASA) is a saccular bulge of the interatrial septum (>10–15 mm excursion) into one or both atria. Often incidental on echo.

Stroke Risk

Most ASAs are benign. However, large ASA (>15 mm) + patent foramen ovale (PFO) + atrial arrhythmia increases cryptogenic stroke risk via:

• Thrombus formation in the aneurysmal sac (stasis).
• Paradoxical embolism through PFO.
• Atrial fibrillation/flutter (associated with ASA).

Transient Ischemic Attack (TIA)

Temporary neurologic deficit (<24 hrs, usually <1 hr) from transient cerebral ischemia. Warning sign for stroke.

Evaluation & Management

• Imaging: TEE (gold standard for ASA/PFO), TTE, MRI brain if stroke/TIA.
• Monitoring: Serial echo for size/mobility change.
• Antithrombotic Therapy: Antiplatelet (aspirin) for cryptogenic stroke + PFO/ASA. Anticoagulation if AFib.
• PFO Closure: Considered in select cryptogenic stroke patients 18–60 with PFO + ASA (per RESPECT, CLOSE, REDUCE trials).
• Surgical Repair: Rare; for giant ASA with thrombus or recurrent emboli despite anticoagulation.

Shared decision-making with cardiologist/neurologist is essential.