What is the recommended treatment for a patient with an atrial septum aneurysm?

Management of Atrial Septal Aneurysm

For patients with an isolated atrial septal aneurysm without associated conditions or prior embolic events, no specific antithrombotic therapy is recommended.

Definition and Prevalence

Atrial septal aneurysm (ASA) is defined as a congenital malformation of the atrial septum characterized by bulging of the septum overlying the fossa ovalis region into either atrium, with an excursion of >10 mm beyond the plane of the atrial septum 1. The prevalence of isolated ASA is estimated at 2-3% of the adult population 1.

Clinical Significance and Risk Assessment

ASA's clinical significance varies based on associated conditions and patient characteristics:

• Isolated ASA: In asymptomatic patients with isolated ASA (without patent foramen ovale or other cardiac abnormalities), the risk of stroke is relatively low
• ASA with PFO: Significantly increases stroke risk, particularly in younger patients (<55 years)
  • The odds ratio for ischemic stroke in patients <55 years with both PFO and ASA is 15.59 (95% CI, 2.83-85.87) compared to those with neither 1
  • For patients >55 years with both PFO and ASA, the odds ratio is 5.09 (95% CI, 1.25-20.74) 1

Management Algorithm

1. For Asymptomatic Patients with Isolated ASA

• No antithrombotic therapy is recommended 1
• Regular cardiac follow-up may be reasonable to monitor for development of associated conditions

2. For Patients with ASA and History of Cryptogenic Stroke/TIA

• If ASA is associated with PFO:

  • Age 18-60 years: Consider PFO closure plus long-term antiplatelet therapy over antiplatelet therapy alone 1
  • Age >60 years: Antiplatelet therapy alone is recommended 1

• If ASA exists without PFO:

  • Antiplatelet therapy (aspirin 50-100 mg/day) is recommended 1
  • If recurrent events occur despite aspirin therapy, consider vitamin K antagonist therapy (target INR 2.5; range 2.0-3.0) 1

3. For Patients with ASA and Evidence of DVT

• Vitamin K antagonist therapy for 3 months (target INR 2.5; range 2.0-3.0) 1
• Consider device closure if appropriate 1

Special Considerations

Diagnostic Evaluation

• Transesophageal echocardiography (TEE) is superior to transthoracic echocardiography for diagnosing ASA 2
• TEE has identified ASA in 47% of cases where transthoracic echocardiography missed the diagnosis 2
• When ASA is identified, careful evaluation for:
  • Patent foramen ovale (most common associated abnormality) 2
  • Atrial septal defects
  • Mitral valve prolapse

Potential Mechanisms of Embolism

1. Thrombus formation within or around the ASA (rare finding on imaging) 2
2. Paradoxical embolization through an associated interatrial communication 3
3. Associated mitral valve prolapse 4

Monitoring and Follow-up

• For patients with isolated ASA without treatment: Regular cardiac evaluation to detect any changes
• For patients on antiplatelet or anticoagulant therapy: Standard monitoring for medication efficacy and adverse effects
• For patients who undergo PFO closure: Follow-up echocardiography to confirm device position and absence of residual shunt

Conclusion

While isolated ASA has been associated with embolic events in some studies 5, 4, 2, 3, current guidelines do not recommend routine antithrombotic therapy for asymptomatic patients with isolated ASA 1. Treatment decisions should focus on the presence of associated conditions (particularly PFO), history of embolic events, and patient age.