cycling may not be the right sport for people that have tendencies for hypochondria. A certain class of medical researchers likes to try to find ways that cycling is bad for you. For example, I don't know how many studies we need to show that cycling is bad for having kids. And then they went through the cycling is bad for your bone density stage. Now we are going through the cycling is bad for your heart stage. I expect to rinse and repeat the above subjects and more.
There are known bad effects on the heart of ageing endurance athletes. However, they aren't as bad as the bad effects on your heart of sitting on the couch eating moon pies and drinking RC cola.