I just had a physical last week and had an EKG taken. I too have a very fast heart rate, but the doctor said it was nothing to be concerned about. It can be caused by a number of things, anxiety for one. Also, smoking causes an increased heart rate, as does not exercising (if that makes sense). The better shape you're in, the lower your heart rate. I would check with your physician, but I am sure it is caused by anxiety. Also, what made me feel better is that my dr. says she also has a very fast heartrate.