You might want to get another opinion. We did after the mitral valve became an issue. I believe she might have had more time if we had sought the 2nd opinion earlier. Still, living to 92 mostly in good health is not too shabby. The second opinion doc said he would have repaired the mitral valve earlier and we were trying to get her into a hospital that had an experimental operation to repair the valve through a catheter. In the end, she simply wasn't well enough to get her evaluated for the new procedure in another hospital. You might look for an opinion at a teaching hospital.
My Mother had aortic valve replacement (pig valve) and double bypass at the age of 86. She had a few set backs, i.e., blood clot in her leg, shortness of breath, and her full recovery took about 6 months. She lived another 6-1/2 years and ultimately died because her mitral valve was leaking badly -- the surgeon didn't correct it at the original surgery because it was mild -- and she developed heart failure. This all came after a bout of pancreatitis. The 6-1/2 years were good ones, she only took a thyroid pill and an asprin for most of that time. She was fairly healthy at the time of her surgery. So don't give up. My mother was extraordinarily positive and I believe that helped her through the experience. Good luck to your Dad.
exersise, cardio.
start him slow then let him work his way up the excersise latter.