Some studies have found that patent foramen ovales (PFOs) are more common in people with unexplained strokes and migraines with aura. A patent foramen ovale is a small hole in the heart that may increase risk of stroke.Learn about how a PFO affect stroke risk. PFO could be a cause or coincidence of stroke. Patent foramen ovale (PFO) is a hole between your heart's upper chambers. Patent foramen ovale (PFO) or hole in the heart, affects millions of people and can cause a stroke. Stroke is the major potential complication of PFO. People who have a PFO are slightly more likely to have a stroke than people who do not.