I had a similar experience about five years ago. Out on our annual New Year's Day ride, I passed out just outside of town. In determining why I passed out, they discovered significant blockage. Shortly I had five bypasses, thanks to the surgeons at St. Thomas Hospital in Nashville. They said biking saved my life, as if I had not passed out, I was looking at a major cardiac event. Further, with biking my heart was actually in good shape and I had some very good veins and generally good health to aid my recovery.

I now keep my heart rate down with a beta blocker. Can't ride as hard or climb like I once did, due to not being able to get my heart rate above 115, but at least I'm riding. Tend to do shorter rides, but get in about 3,000 miles a year. Not too bad for a 66 y/o has been.