Ten years ago I also started having problems with my heat speeding up over and over again. It would start with a premature heart beat and then go up so fast I would get dizzy. They ran lots of tests and found nothing wrong. I started having anxiety attacks because of it. I was getting to the point of not wanting to go anywhere.
I started taking Ziac (a beta blocker) and that helped a lot but I still had the premature heart beats and was very uncomfortable about being by myself.
I got tired of being that way so I forced myself to do things more and more until I could finally go by myself.
I still have premature heart beats but I have grown used to them. I have lived ten more years and I am still here, I do think that when these things happen to your heart that they are hard to overcome but it can be done.

A couple of years ago I started taking coq 10. After taking it for about a month I noticed that I wasn't getting as many premature heart beats. I mentioned it to my doctor and he said I should take more than I was taking.
I am not sure but I think that coq 10 thins the blood so it is not for everyone.

The link below looks like a good link that you might check out.
Wish you the best of luck. Don't give up things will get better.

http://www.medhelp.org/forums/cardio/archive/6462.html