I didn't have any trouble with the stress test. (They did both the resting and stress portions in the same day though. I wish I had brought my Ipod to help with the three hour wait between tests). And they gave me a chemical instead of using the treadmill because I wouldn't have lasted three minutes with my angina. That was weird - I felt like I'd just run a 5K without moving a muscle (but no angina to speak of).
As others have noted here though, you've nothing to worry about. They monitor you very closely on the treadmill and will shut it down at the first sign of real trouble.
I understand your fears, but this really is not as bad as you fear it will be. First of, relax, that will help you more tomorrow than anything. I've had a couple of these and I really stressed over the first one, really not a big deal.
Secondly, don't fear the results. Remember, knowledge is power. Keep in mind, the evil you know is better than the evil you fear. Once you have the true knowledge of your condition, you can move forward. I would personally be more afraid of not having the test. You will most like find out nothing is wrong and just imagine what a relief that will be.
You'll do great! Let us know how it goes.
Jon
Just to add. I have had 2 persfusion scans. The first was using the treadmill and the second was using drugs to stress my heart because my angina was too bad for the walking. I can tell you I would choose the treadmill option every time if I could. Those stress inducing drugs sure can give you chest discomfort.
The idea of the treadmill is to get your heart to the optimum rate for you (which they will calculate). If I stand up, my pulse suddenly jumps to around 80-90 but that isn't a problem, it's good. It then quickly drops back down to about 74. The speed of reaction is what's important. The treadmill is fine, nothing to worry about and you have to remember they are monitoring your heart all the time because you are hooked up to an ecg monitor.
You could look at it as good exercise :)
If they see anything worrying, i.e. any changes in the ecg, they still stop the treadmill.