You seem to be having a lot of symptoms that are causing you a lot of discomfort. Although you have had a lot of tests that have not shown anything, there are other things that can be done to help determine if you are truly having an arrhythmia. There are a number of conditions that can cause a fast heart rate (with/without symptoms) that can happen spontaneously -- supraventricular tachycardia, atrial fibrillation, atrial flutter, atrial tachycardia, to name a few. Sometimes these conditions can be paroxysmal and not caught on an ECG or even a 24 hour holter. If you are fainting with these symptoms, this could represent a serious problem that should be addressed. A loop recorder or even a heart monitor (that monitors more than 24 hours) may be indicated.
About 3 months ago, my heart started racing again. I would get dizzy and so dizzy I would almost fall down. I was having chest pains, sometimes a tingly feeling in my left arm. But it does not happen all of the time, Sometimes it might be once a week, to maybe once a month. Sometimes more frequent. I have a heart monitor on and it did not pick it up because it was only 24 hours. Also I had a chemical stress test done, because I was on the beta blockers. So my heart rate never really got up very high on the stress test. But basically what the doctors are telling me now, that it is all in my head. I don't see how it is in my head if am getting so dizzy and sudden headaches and I feel my heart racing fast and hard. But yet the quack of cardiologist said it was in my head. I was even treated for anxiety and I was still having the same problems. Does anyone have any ideas?