Sending prayers to your dad. My father had a heart attack in 2002 and had to have a quadruple bypass done. He was 59. He went through it with flying colours and he is diabetic so he tends to take longer to heal. Although he did not go back to work after, he does body work in his garage everyday and that was after having a 2nd heart attack in 2007 (three stints that time plus they lost him on table for a bit and had to bring him back). He is a stubborn man and refuses to moderate himself or quit smoking (or quit eating sweets, he still has a chocolate bar every night before bed even though he is on insulin for his diabetes).
Heart surgery is more common now, and recovery time is faster than it was years ago, but hearing that doesn't make it less scary. Hope everything goes well.