Depending on how bad it is, you can probably live another 5-10 years. My father-in-law had congestive heart failure at the age of 75 after a lifetime of smoking, heart attack at 50, and some kind of fever that he caught in Vietnam that sent him home before he saw any action but damaged his heart. He died in the hospital at 83 after a quadruple by-pass surgery. He woke up from the surgery but died soon after. I think it was the doctors trying to pump the last few $$$ out of him.
I wish you well on your journey with your health.
Your father-in-law sounds like me! He probably had Malaria like I do, it's the only fever I can think of that came out of Nam. I've had one heart attack in 2014 and I smoke, but have cut way down (it's hard to kick). I'll be 73 in a couple of weeks God willing!