What can a cardiac MRI find in the overall treatment of my patent foramen ovale (PFO)?

Role of Cardiac MRI in PFO Treatment

Cardiac MRI has limited utility in the overall treatment of patent foramen ovale (PFO) and is inferior to transesophageal echocardiography (TEE) for detection of right-to-left shunting, with only 18.8% of mild shunts detected by TEE being identified by MRI. 1, 2

Diagnostic Capabilities of Cardiac MRI in PFO Management

Strengths of Cardiac MRI

• Can quantify right-to-left shunting in more severe cases 1
• Useful for detailed visualization of atrial septal anatomy before PFO closure 1
• Can detect associated atrial septal aneurysm, which increases embolic risk 1
• Can be used for planning transcatheter PFO closure procedures 1
• Can exclude anomalous venous returns and identify coronary anomalies 2

Limitations of Cardiac MRI

• Significantly less sensitive than TEE for detecting mild shunts 2
• Inferior to TEE for identification of atrial septal aneurysm (37.3% detection with MRI vs 62.7% with TEE) 2
• Cannot reliably detect contrast-enhanced right-to-left shunting in mild cases 2

Preferred Imaging Modalities for PFO Assessment

Initial Screening

• Transcranial Doppler (TCD) with bubble study and Valsalva maneuver is recommended for initial screening 1
• Transthoracic Echocardiography (TTE) with bubble study and Valsalva maneuver is useful for initial detection 1

Definitive Diagnosis

• TEE with bubble study remains the gold standard for:
  • Confirming PFO presence
  • Assessing right-to-left shunting
  • Providing detailed visualization of atrial septal anatomy
  • Essential evaluation when PFO closure is being considered 1

Clinical Applications in PFO Treatment Pathway

Pre-Closure Assessment

• TEE is the primary imaging modality for pre-closure assessment 1
• Cardiac MRI may provide complementary information about:
  • Atrial septal anatomy
  • Quantification of significant right-to-left shunting
  • Detection of associated cardiac anomalies 1, 2

Post-Closure Monitoring

• Brain MRI can be used to detect silent cerebral ischemic lesions before and after PFO closure 1
• Cardiac MRI can be used to monitor for new silent lesions after PFO closure 1

Clinical Considerations for PFO Management

• PFO closure may be considered particularly in patients ≤60 years with high Risk of Paradoxical Embolism (RoPE) scores (>6) 1
• The presence of atrial septal aneurysm increases embolic risk and may influence treatment decisions 1
• Recent randomized control trials have demonstrated that PFO closure in patients with cryptogenic stroke is associated with reduced rates of recurrent stroke compared with medical therapy 3

Practical Approach to PFO Imaging

1. Initial screening with TTE with bubble study and Valsalva maneuver
2. If PFO suspected, proceed to TEE with bubble study for definitive diagnosis
3. Consider cardiac MRI as a complementary tool for:
   • Planning complex closure procedures
   • Evaluating associated cardiac anomalies
   • Quantifying significant right-to-left shunts
4. Use brain MRI to detect silent cerebral ischemic lesions before and after closure

In summary, while cardiac MRI has some utility in the management of PFO, it should be considered a complementary tool to TEE, which remains the gold standard for diagnosis and pre-closure assessment.