What is the recommended management for a 13-year-old female with a patent foramen ovale (PFO) of 6.5 mm and a left to right shunt?

Management of 6.5 mm PFO with Left-to-Right Shunt in a 13-Year-Old Female

Observation with Clinical Monitoring is Recommended

In an asymptomatic 13-year-old with an incidentally discovered PFO and left-to-right shunt, no intervention is indicated—observation with periodic clinical assessment is the appropriate management strategy. 1, 2

Key Clinical Context

This case fundamentally differs from the evidence-based indications for PFO closure, which specifically apply to:

• Patients under 60 years with cryptogenic stroke (not applicable here—no stroke history) 3, 1
• Documented right-to-left shunting (this patient has left-to-right shunting, which is the opposite direction) 3

The direction of shunting is critical: left-to-right shunts do not carry the same embolic stroke risk as right-to-left shunts, since blood flows from the systemic (left) to pulmonary (right) circulation rather than allowing venous thrombi to bypass the lungs and reach the brain. 3, 4

Why This PFO Does Not Require Closure

Absence of Stroke History

• All major guidelines recommend PFO closure only after cryptogenic stroke in carefully selected patients under 60 years 3
• The Canadian Stroke Best Practice guidelines explicitly state that PFO closure is not recommended for primary stroke prevention 3
• Incidentally discovered PFOs in asymptomatic individuals require only reassurance 1, 5

Wrong Shunt Direction

• The stroke prevention trials (CLOSE, REDUCE, RESPECT) enrolled patients with right-to-left shunts, not left-to-right 3
• Right-to-left shunting allows paradoxical embolism (venous thrombi reaching arterial circulation), which is the mechanism of PFO-related stroke 3, 4
• Left-to-right shunting does not create embolic stroke risk through this mechanism 3

Size Alone is Not an Indication

• While this 6.5 mm PFO is moderately sized, size alone without symptoms or stroke history does not warrant closure 3, 1
• The trials demonstrating benefit required both PFO presence AND either atrial septal aneurysm (>10 mm excursion) or large right-to-left shunt (>30 microbubbles or >25 microbubbles depending on trial) 3, 1

Recommended Monitoring Strategy

Initial Evaluation

• Transthoracic echocardiography with bubble study and Valsalva maneuver to confirm shunt direction and assess for atrial septal aneurysm 1, 2
• Pulse oximetry at rest and with exercise if any concern for positional right-to-left shunting develops 3
• ECG and chest X-ray for baseline assessment 3

Follow-Up Schedule

• Serial clinical assessment every 1-3 years depending on any symptom development 3
• Repeat echocardiography if symptoms develop suggesting right-to-left shunting (unexplained hypoxemia, platypnea-orthodeoxia, neurological events) 3, 4

Critical Pitfalls to Avoid

Do Not Close This PFO

• PFO closure in patients over 60 years or where PFO is likely incidental is explicitly not recommended 3, 1
• This 13-year-old with no stroke history and wrong shunt direction falls into the "incidental" category 1, 5
• Procedural risks include device-related adverse events (5.9%), atrial fibrillation (4.6%), and pericardial effusion 3, 6

Do Not Start Anticoagulation or Antiplatelet Therapy

• No indication for anticoagulation or antiplatelet therapy exists in asymptomatic patients with incidental PFO 3
• These medications are reserved for secondary stroke prevention after cryptogenic stroke 3

When to Reconsider Intervention

Reassessment would be warranted if:

• Cryptogenic stroke or TIA occurs after age 16-18 years with documented right-to-left shunt 3
• Symptomatic right-to-left shunting develops (positional hypoxemia, platypnea-orthodeoxia syndrome) 3, 4
• Recurrent paradoxical embolism with documented deep venous thrombosis 5

In such scenarios, the patient would then meet criteria for consideration of closure with antiplatelet therapy, with number needed to treat of 20 over 5 years to prevent one stroke. 3, 1