I've been aware of an online patient support community called Cardiac Athletes for a while now. I got an email yesterday from Lars Andrews, their chief cardiac physiologist asking if I'd spread the word about their site.
Taking a look, the site brings together athletes from around the world with various heart conditions. There is some general information that will be useful to athlete patients, but the biggest opportunity here is the Forum, where athletes can connect with each other about their medical conditions.
So check out www.cardiacathletes.com.