one of my teammates just received the same diagnosis (the week before the Death Ride, mind you). her cardiologist did not tell her to stop riding, but she is watching her HR.

ironically, as we were doing the ride, she ran into a friend of her who'd also had the same diagnosis and ultimately had valve replacement surgery.

anyway, just make sure your doc knows what you are doing training wise and make sure they haven't got any limitations (which it seems they don't). you may have a more mild case.