Originally Posted by Carbonfiberboy

The evidence suggests that it's not simply riding a lot that can damage the heart with time. Rather it's repeatedly taking it to the limit on long endurance events or doing as many intervals as recovery allows for many years. Or fartlek, that sort of thing. I have 3 friends who can no longer go hard due to Afib. They are poster boys for the mentioned practices. They still ride, but slower. I had a cardiologist who'd worked with cycling teams really give me the lecture about 15 years ago. Going hard is fine. Riding a lot is fine. But constantly going hard may not be fine. The running story is an analogue. As much as the OP is riding, it's probably not an issue for him.