It depends on a lot of things, starting with his physical and mental shape. If your husband is positive about the replacement and the doctor is willing to do the surgery, I think that is a good base to go for it. Discuss with your doctor what the risks are and what you can expect. Good luck!
This is a discussion you need to have with your husbands cardiologist/surgeon. I'm sorry I couldn't give you a better answer than that because I know you must be very concerned, but only the doctor is going to be able to answer that question.
I wish your husband the very best outcome and for YOUR peace of mind, talking to the doctor as soon as you can will help.
RW