Thanks for the reply. I don't smoke, and I'm overweight, but not by much (I'm 5'10" 195lbs, but fairly broad-shouldered, so I don't put too much stock in the BMI results the calculator gives me). I've heard the "don't exercise harder than a level which would allow you to have a conversation" suggestion, but even when I'm on the elliptical with a steep incline, I'm pretty sure I could still speak to someone without much effort! I spoke with an aortic surgeon and he recommended a CT scan again in 6 months, while the cardiologist only recommended an echo. I'm wondering if he wants a CT this time just to check growth rate, and if it isn't that high, then maybe he'll switch to recommending just echos? It's obviously a less-pressing concern right now, but I don't want to end up Chernobyling myself because of this, either.