Hi Sally, I can understand your concern as I also was concerned leading up to one I just had. I see you said you failed one, May I ask which type you failed? Also I know the goal is to raise your heart rate to what is called 85 % of what's normal for your age. In my case at 63 they wanted to get to 133 BPM and we succeeded with the chemical version. So for me with a history of arrhythmias with my old heart ( i am a heart transplant paient) I was pretty stressed going in. But with the completion of the test it gave me more confidence. I also was in the right place to have an issue if it happened. So, was the reason your first test was unsuccessful because they could not reach the level they wanted too?