Well, if it is a blockage, you definitely do not need to restrict your cycling after it's "fixed." My husband had 2 stents put in in June 2005. He was (and is) super fit, but is the victim of horrible genetics and starting way too late on the exercising/eating right. In fact, his nuclear stress tests NEVER show any blockages and it took him practically grabbing the cardiologist by the neck to insist on an angiogram. He was walking 2 miles 3 days after surgery, riding flat 13 miles after 5 days and after a week he met me on a ride I was leading in Harvard MA (can you say hills?). Now, he did keep his HR down for about 6 weeks and the doctor was not really thrilled, but he didn't say stop. After about 6 weeks, he was told to do whatever he had been doing before. Being on Plavix (blood thinners) does cause bruising from even the tiniest little bump, but it hasn't gotten in the way of anything. We had one crash last winter where his elbow swelled up; we knew it was from the drug, so we rode to the ER to get it checked out!
No one who looked at my husband would think he had cardiac issues; just because you are fit doesn't mean this can't happen.