I hope you have not "got a handle on it" - as the anxiety will likely give you some heart symptoms that will just confuse things.
What do you mean by "acting up"? Irregular, fast, pounding... what? Does it feel like past PVCs? If so they have been diagnosed and determined not to be life threatening.. if that helps with the anxiety, believe it.
The way I get a handle on it when my heart acts up is to take 50mg atenolol and 1mg of Xanax. That pretty much slows my heart rate to a turtles speed and kills the anxiety with one mighty punch. Although when the next day comes around, its back to acting up and skipping beats. Recently I have tried to just ignore mine and come to the conclusion if it gets serious there is nothing I can really do about it anyways