I have had an Arrhythmia for more than 25 years (I'm 40 now). It would occur, at most, a couple times a month. I finally decided to see a specialist who gave me a portable monitor for a month. We were only able to record one major event and two small ones for the entire month. I don't know the name of my condition, but it feels like my heart is having spasms, and it turns out that it's just extra heartbeats. I was told that it was not a health risk and medication was not recommended.
Several weeks later, I went to the Dentist and had a Root Canal. Suddenly, I was having events all the time. I couldn't walk out to get the mail without an occurrence. It was happening 5 to 15 times a day and it never used to happen with exercise. The change was incredible. During the first week I tried to think of what could have triggered this and the only thing that I could think of was the Root Canal. I did a web search and found the following hit in your Forum:
http://medhlp.netusa.net/perl6/cardio/archive/5648.html
While the start of my episode matched the start of my root canal, I didn't use any antibiotics. My brother-in-law is a Dermatologist and he thinks the Epinephrine in Novocain is probably the cause and the drug reference states that Epinephrine can cause heart Arrhythmias. One month after the Root Canal, the Arrhythmia's stopped like a switch and I'm back to my normal Arrhythmia pattern.
In my case, and in the referenced Forum, we experienced a one-month period of intense Arrhythmias after a Root Canal (and Novocain). In both cases, it started and stopped very suddenly. Maybe there's something here worth studying. Is there a possible connection?