From an article on a Fitness Instructor’s stroke
Fortunately for Jessica, she woke up the next day with feeling in her left leg and few other symptoms than a little grogginess and fatigue. While she had no previously known medical issues, doctors discovered what they believed caused Jessica’s stroke as a PFO, or patent foramen ovale, a small hole in heart that had been undetected all her life and a blood condition called Factor 5 Ledion [Leiden], making her more prone to clotting. Jessica’s team of physicians, have recommended she undergo surgery to close the hole in heart, which she will proceed with this spring and she is taking an asprin a day to regulate blood clotting.
The frequency of the congenital heart defect patent forman oval (PFO) is between 20-30% based on post-mortem studies of normal hearts. The most common Factor V Leiden mutation related to thrombosis has an occurrence of 4.4%1 in Europeans and Caucasions (one of the most common monogenic disorders in the Caucasian population).
Combining those gives a range of 0.8% and 1.3% for having the condition and the mutation. This is surely an oversimplification of the probability, but this seems remarkably high, and could combine with other factors to increase the risk of blood clots. Since her doctor recommending heart surgery, she may have two copies of the Factor V disease variant or other unmentioned factors.
Earlier PFO estimates were 10-15%. Recent higher estimates draw suspicion about this as a causative factor for embolisms. Here’s a counterpoint on the “indictment of the PFO as a source of embolic stroke”.