I think your chances of surviving a double-valve transplant are excellent! As CCFHeartMD 12 advised, take great care in choosing your surgeon and the facility that will do your surgery.
I have had three surgeries, the first two taking place when I was 24 years old in 1975. I had both the aortic and mitral valve replaced with mechanical valves at St. Lukes in Houston TX by the world renowned surgeon, Denton Cooley. That was 37 years ago and I'm still going strong.
In 2006, surgeons had to go in again and replace the old, aortic mechanical valve with a new St. Jude.
I know you will do just fine! Best of luck to you!
Terry: sounds like you are in need of a re-do operation with mitral and aortic valve replacement. You are 63 years young, with history of MV repair and atrial fibrillation. I think that the risk of re-do MVR and first time AVR plus or minus a coronary bypass remains reasonable -- but really depends on your other medical issues, heart muscle function and physical fitness. All of the above you really have no control over at this point, but you do have control over one more factor --- the surgeon and the institution that would be involved in your surgery.
I do not like to self-promote, but I have seen very good results with patients like you (e.g. needing second or third open-heart surgery) here at the Cleveland Clinic. I believe nationally we have one of the best outcome records when it comes to cardiac surgical success rates. I have a lot of faith in my surgical colleagues and would refer myself or my family members here if needed.
Discuss with your cardiac consultant and ask him or her to for a recommendation. Consider Cleveland Clinic as well. Good Luck!