heart covered in fat couldn't be completely repaired, what are the risks still?

My 74 year old father had four of the seven blockages repaired in open heart surgery yesterday and the doctor said he was unable to repair the other three because the heart is covered in fat and the arteries are embedded in fat.  Just wondering if he still is at risk of heart attack should those three other arteries completely close off.  I am still a little uncomfortable.  The doctor pointed out he gave him four more arteries that he did not have before, I am just uncomfortable about the other three still.  Thank you so much for any information.  I am so grateful for your knowledge and dedication to your profession.