I've had an irregular rapid heartbeat on occasion, and it was recently diagnosed as atrial tachycardia. The cardiologist said this is not life threatening (unlike atrial fibrillation, which can lead to stroke), yet he wants to keep it under control with sotalol (a beta blocker). Given that my rapid heartbeat only occurs on occasion and doesn't last too long when it happens, I'd rather deal with the rapid heartbeat than suffer with the reduced performance from the beta blockers.
I asked him why he wanted to keep it under control and did not get a good answer, in my opinion. So I am in the process of getting a second opinion from another cardiologist as to recommended treatment.
I noticed many folks here are taking beta blockers for various conditions. Had you considered alternative medications, and if not, why not?