I am so sorry to hear this about your dad. Have FAITH!!!
My dad was 86 yrs old when he died, and he was told at the age of 69 that he had only 26% use of his heart. He just really slowed down, did alot of sitting instead of standing, a nap every afternoon, and went to bed early, and he lasted 17 years like that. SO HAVE FAITH!!!! They have some really great drugs out there now adays that can help him tremdously.
Good luck and my prayers are with you...