Gord, from what I have read about 20% of Americans are living with a PFO. If it were a major risk for stroke I think it would get a lot more attention than it does. Up until I had an echocardiogram, I didn't know whether I had a PFO; I don't, just a leaky valve. So, there may be a lot of people who could say "I have the same thing and I go out for weeks at a time" but can't because they don't know. The link below is informative but I'm sure you have already seen it. Good wishes to you.

http://www.stroke.org/site/PageServer?pagename=PFO
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May I walk in beauty.