Is patent foramen ovale a modifiable risk factor for stroke recurrence?

Area of Science:

• Cardiology
• Neurology
• Epidemiology

Background:

• Patent foramen ovale (PFO) prevalence is ~25% in the general population, but ~50% in cryptogenic stroke (CS) patients.
• PFO closure is often recommended for CS patients to prevent stroke recurrence, primarily due to the hypothesis of paradoxical embolism.
• The actual benefit of PFO closure and the role of paradoxical embolism in CS stroke recurrence remain unclear.

Purpose of the Study:

• To critically review the epidemiologic evidence linking PFO to stroke recurrence in CS patients.
• To evaluate whether PFO is a modifiable risk factor for stroke recurrence in CS.
• To introduce and assess the concept of "PFO propensity" for patient stratification.

Main Methods:

• Review of epidemiologic data on stroke recurrence in CS patients with and without PFO.
• Analysis of stroke recurrence rates based on shunt size (large vs. small right-to-left shunts).
• Introduction and definition of "PFO propensity" based on patient age and other risk factors.

Main Results:

• Epidemiologic findings are difficult to reconcile with paradoxical embolism as the sole cause of stroke recurrence in CS.
• Evidence suggests that strokes in CS patients with PFO are sometimes PFO-attributable and sometimes unrelated to PFO.
• "PFO propensity" is directly related to the probability that CS is PFO-attributable.

Conclusions:

• Substantial heterogeneity exists in PFO propensity and recurrence risk among CS patients with PFO.
• Stratifying CS patients for PFO closure based on "PFO propensity" and recurrence risk is crucial for appropriate patient selection.
• This approach may optimize the use of PFO closure interventions.