Why don't you go to your cardiologist and find out if there are any protocols you need to follow?
For what it's worth, my DH has 2 stents, although he did not have a heart attack, just 2 80% blockages. He was riding up hills 10 days after his surgery. What you had is totally different, but, you need to find out answers from a cardiologist who knows something about athletes and sports medicine. Unless they do, physicians are going to tell you the most conservative advice they can. If you live in or near a major metropolitan area, you should be able to find someone who knows about cardiology and cycling.