No, You Do Not Have a 33% Risk of Stroke
The fact that one-third of patients have a patent foramen ovale (PFO) does NOT mean you have a 33% risk of stroke. This is a critical misunderstanding of what prevalence means versus actual risk.
Understanding the Numbers
The ~33% figure refers to how common PFOs are in the general population—approximately 20-33% of all people are born with this small opening between the heart's upper chambers 1. This is simply a prevalence statistic, not a risk prediction.
Your Actual Stroke Risk With PE and PFO
If you have both pulmonary embolism AND a PFO, your stroke risk is elevated but still relatively modest:
- Recent ischemic stroke occurs in approximately 19-21% of PE patients who have a PFO 2, 3
- This compares to only 4-5.5% in PE patients without PFO 2, 3
- The presence of PFO increases stroke risk by roughly 5-fold in the setting of acute PE 2
Why PFO Matters in Your Situation
When you have a pulmonary embolism, the clot increases pressure in the right side of your heart. This elevated pressure can temporarily reverse blood flow through a PFO, allowing clots to bypass the lungs and travel directly to the brain—a phenomenon called paradoxical embolism 4.
Key risk factors that increase concern:
- Larger shunt size through the PFO
- Presence of an atrial septal aneurysm (excessive bulging of the heart wall)
- Ongoing right heart strain from the PE
- Deep vein thrombosis as the source 4
What This Means for You
The critical distinction: Having a PFO alone in healthy people does NOT increase stroke risk 1. The Northern Manhattan Study and Olmsted County SPARC study both confirmed that asymptomatic people with PFOs have no increased stroke risk compared to those without 1.
However, in the context of your recent PE:
- You face a temporarily elevated stroke risk while the PE is active
- This risk is highest during the acute phase when right heart pressures are elevated 5, 6
- Proper anticoagulation for your PE is the primary protective measure
- The stroke risk diminishes as the PE resolves and right heart pressures normalize
Clinical Implications
Your medical team should:
- Ensure adequate anticoagulation for your PE
- Consider transesophageal echocardiography to characterize the PFO size and any associated features 4
- Monitor for any neurological symptoms during the acute PE phase
- Discuss whether PFO closure is appropriate after PE resolution (though this is typically reserved for patients who have already had a cryptogenic stroke) 4
Bottom line: The 33% statistic describes how common PFOs are in the population, not your personal stroke risk. Your actual stroke risk is elevated due to the combination of PE plus PFO, but this is a manageable, time-limited risk that decreases as your PE is treated.