Know Your Risk Before It Strikes
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Quick Answer
Yes. A hole in the heart, most commonly a patent foramen ovale (PFO), can increase the risk of stroke. It may allow a blood clot to bypass the lungs and travel directly to the brain, causing an ischemic stroke. However, most people with a PFO never experience complications.
Hearing that you have a hole in your heart can feel alarming. For most people, it is not dangerous. About 1 in 4 adults has this condition, known as a patent foramen ovale (PFO), and the majority never know it is there.
That said, for a smaller group of people, a PFO can raise the risk of stroke. Understanding how that happens and what it means for you is the first step toward making informed decisions about your health.
What Is a Hole in the Heart?
Before birth, all babies have a small opening between the two upper chambers of the heart. This opening, called the foramen ovale, serves an important purpose. Since a baby in the womb does not breathe, the lungs are not active. The opening allows blood to take a shortcut, skipping the lungs and going directly to the rest of the body through the placenta and umbilical cord.
When a baby is born and takes that first breath, blood pressure shifts and the opening usually closes on its own. In most children, it seals completely within the first few months of life. In about 25% of people, it never fully closes. When that happens, the condition is called a patent foramen ovale (PFO). The word patent simply means open.
PFO vs. Atrial Septal Defect (ASD)
PFO is often confused with an atrial septal defect (ASD). Both involve openings between the heart’s upper chambers. The key difference: a PFO is a flap-like remnant from fetal development, while an ASD is a true structural hole in the wall between the chambers. ASDs are less common and often require treatment. You can read more about structural heart defects and how they are managed.
How Can a PFO Cause a Stroke?
The Clot Pathway Explained
Normally, blood returning from the body passes through the right side of the heart and then goes to the lungs. The lungs act as a filter, catching small clots and harmful particles before blood moves to the left side of the heart and out to the body.
With a PFO, that filter can be bypassed. Here is how it happens:
- A blood clot forms, often in the legs (a condition called deep vein thrombosis, or DVT).
- The clot travels through the bloodstream to the right atrium of the heart.
- Instead of going to the lungs to be filtered, the clot slips through the PFO into the left atrium.
- The clot travels from the left side of the heart up to the brain.
- It blocks a blood vessel in the brain, causing an ischemic stroke.
This process is called a paradoxical embolism. It is called paradoxical because the clot starts in the venous (returning) side of circulation but ends up in the arterial (outgoing) side, which does not normally happen. Learn more about ischemic stroke and its causes.
What Is a Cryptogenic Stroke?
A cryptogenic stroke is a stroke with no known cause. Doctors cannot identify a clear source such as blocked arteries, atrial fibrillation, or a clot from another known origin. About 25 to 30% of all ischemic strokes fall into this category, according to data cited by Abbott Structural Heart.
PFO is often discovered after one of these unexplained strokes. In people under 60 who have had a cryptogenic stroke, 30 to 50% are found to have a PFO. That is why doctors frequently test for PFO after a stroke with no obvious cause, especially in younger patients. The American Heart Association notes that PFO prevalence rises to 40 to 50% in cryptogenic stroke patients.
Who Is at Higher Risk?
Most people with a PFO do not have an elevated stroke risk. Certain factors can make stroke more likely in someone who has one. Risk increases when these factors are present:
Large PFO size. The bigger the opening, the greater the chance a clot can slip through.
Deep vein thrombosis (DVT). Clots forming in leg veins are a primary source of paradoxical emboli.
Obesity. Obesity raises the overall risk of clot formation and cardiovascular complications.
Sleep apnea. Breathing pauses during sleep can cause pressure shifts in the chest, forcing blood across the PFO. Read about sleep apnea and arterial damage.
Pregnancy. Pregnancy creates pressure changes that can push blood through a PFO.
Long periods of immobility. Long flights or bed rest can promote clot formation in the legs.
Genetic clotting disorders. Conditions like Factor V Leiden or Protein C/S deficiency increase clot risk. See genetic risk factors for heart disease.
Pressure shifts. Straining during heavy lifting, bowel movements, or childbirth can force blood rapidly through a PFO, pushing a clot through before it can be caught.
Stroke Warning Signs: Act Immediately
EMERGENCY: If you or someone nearby shows stroke symptoms, call 911 immediately. Every minute matters.
Use the FAST method to recognize a stroke:
F – Face drooping. Is one side of the face drooping or numb? Ask the person to smile.
A – Arm weakness. Is one arm weak or numb? Ask them to raise both arms.
S – Speech difficulty. Is speech slurred or hard to understand?
T – Time to call 911. Do not wait. Call emergency services right away.
Other symptoms include sudden vision loss, severe headache, numbness on one side of the body, or sudden confusion. Our stroke prevention program covers risk reduction in detail.
How Is a PFO Diagnosed?
PFO is most often found after an unexplained stroke. Doctors use several tests to confirm its presence. According to the Cleveland Clinic, the main options include:
Transthoracic echocardiogram (TTE). An ultrasound of the heart done from outside the chest wall.
Transesophageal echocardiogram (TEE). A more detailed ultrasound done by placing a probe into the esophagus, which sits right next to the heart.
Bubble study. A salt-water solution with tiny air bubbles is injected into a vein. If the bubbles cross to the left side of the heart, that confirms a PFO.
Transcranial Doppler (TCD). An ultrasound that detects whether bubbles reach blood vessels in the brain.
Do All PFOs Need Treatment?
No. Most people with a PFO need no treatment. Treatment is considered mainly for people who have already had a cryptogenic stroke or who carry significant clotting risk factors. There are two main approaches.
Option 1: Blood Thinners
Blood-thinning medications reduce the chance that new clots will form. Common options include aspirin, clopidogrel (Plavix), and warfarin (Coumadin). These medications do not close the PFO. They lower stroke risk by preventing clot formation. The tradeoff is an increased bleeding risk, and most must be taken daily for the long term.
Option 2: PFO Closure (Minimally Invasive)
PFO closure is a catheter-based procedure. A thin tube is inserted through a vein in the groin and guided to the heart. A small closure device, such as the Amplatzer PFO Occluder or the Cardioform Septal Occluder, is placed to seal the opening.
The procedure typically takes 30 to 40 minutes. Most patients go home the same day. This is not open-heart surgery. The Amplatzer device has been FDA approved and shown to reduce recurrent stroke risk in selected cryptogenic stroke patients. Closure is usually considered when someone has already had a stroke and the PFO is believed to be the cause.
What Is the Outlook for People with PFO?
The outlook is generally positive. Most people with a PFO live normal lives without treatment.
For those who need a closure procedure, the prognosis is also good. According to the Cleveland Clinic, people under 25 who undergo PFO closure have the same life expectancy as others their age without a PFO. In people under 40 with high-risk PFOs, closure can improve quality of life and survival odds. Complications from the procedure are uncommon and usually manageable.
Can a PFO Increase Dementia Risk?
This is an emerging area of research. Harvard Health Publishing reported in 2025 that neurologist Dr. MingMing Ning at Harvard-affiliated Massachusetts General Hospital found that people with large PFOs may face a higher risk of vascular dementia.
The theory is that blood in large PFOs carries higher levels of potentially harmful substances. Over time, these substances may contribute to cognitive decline. This research is ongoing and not yet definitive. If you are concerned about dementia prevention, speak with a cardiovascular specialist who can evaluate your individual risk.
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Frequently Asked Questions
Can you live a normal life with a PFO?
Yes. Most people with a PFO never know they have it and need no treatment. It does not limit daily activities for the vast majority of people.
How common is stroke in people with a PFO?
Stroke risk is low for most people with a PFO. Risk increases with large PFO size, a history of blood clots, or other compounding factors such as DVT or clotting disorders.
What is paradoxical embolism?
A paradoxical embolism occurs when a blood clot from the venous system, usually from the legs, crosses through a PFO into the arterial system and travels to the brain, bypassing the lungs.
Is a PFO the same as an ASD?
No. A PFO is a flap-like remnant from fetal development that failed to seal. An ASD is a true hole in the wall between the upper heart chambers. ASDs are a separate condition and generally require treatment more often.
When should a PFO be closed?
Closure is most strongly recommended for people under 60 who have had a cryptogenic stroke and have a confirmed PFO. Your doctor will consider the size of the PFO, your age, clotting history, and other risk factors before recommending this approach.
Can PFO cause migraines?
Some studies show PFOs are more common in people with migraines with aura. However, Mayo Clinic notes the evidence is not conclusive. In many cases, the association may be coincidental.
Does PFO increase dementia risk?
Emerging research from Harvard suggests large PFOs may increase vascular dementia risk over time. This area is still being studied and is not yet part of standard clinical guidance.
Sources & Further Reading
https://my.clevelandclinic.org/health/diseases/17326-patent-foramen-ovale-pfo
https://www.mayoclinic.org/diseases-conditions/patent-foramen-ovale/symptoms-causes/syc-20353487
https://www.scripps.org/news_items/6609-what-happens-if-you-have-a-hole-in-your-heart-video
About the Author: Christine Cooper
