It's not hard to find examples of endurance athletes who have had to deal with heart problems. Just in Australia, high-achieving triathletes, Greg Welch, Emma Carney, Erin Densham and Chris Legh have all had treatment for serious heart conditions and, in some cases, been forced to cease elite competition. It can sound scary!
I would like to see a study that quantifies the enhanced quality of life enjoyed by endurance runners over the course of their careers. I believe the benefits would far outweigh any costs.