I had one done a few years back (before the heart surgeries). I actually do not remember exactly when, just know it was before the first open heart surgery and after my stent.
I don't even remember the exact symptoms, but I believe it was ordered up as part of things to look at because of a flash pulmonary edema I had.
Anyway, the test is harmless, but they work you pretty hard to stress your heart. I was on a treadmill, they started slow and with no incline to warm you up and then increase both the speed and incline and by the end of the workout phase, you are really huffing and puffing. You are all hooked up to things that monitor your heart rate and BP and there are several nurses and a Dr in the room to make sure you are not pushed too far, but they really do want you to be working hard. The harder you are working, the more your heart is stressed and the better test results you will get. You are only at the really stressful part for about a minute or so.
The rest of the test is a cake walk. You just lay there while the CT scan does it's thing.
The radioactive dye will make you glow for a few hours after the test, but it makes for good conversation.
Just kidding. No glow.
Good luck!
-John