Just a note; there were a number of references to warfarin reducing the number of strokes as you age. This misses the point a little. In studies, it was found that as you age, warfarin reduces the number of ischemic strokes (caused by clots), but also increases the likelihood of hemorrhagic strokes (caused by bleeding [aneurystic]). This is a significant enough effect that mechanical valves (because of the Coumadin) are slightly less safe than tissue valves for patients past retirement age.
However, over the long haul with patients in their fifties, the risks of Coumadin/mechanical and reoperation/tissue seem to balance out equally. In the young, the risk of reops over a lifetime with tissue valves slightly outweighs the risks of clotting/bleeding with Coumadin and mechanical valves. At least, in the most current studies.
But the risks of Coumadin are improving with self-testing, and the risks of reoperation have been declining as well. In twenty years, we'll have the data to know which (if either) was a better choice right now. But it won't be "right now" then, will it?
Heck, if it weren't a crapshoot when all is said and done, what would we have to talk about?
Best wishes,