Dave,
thanks for the post.
Some people have significant fatigue from beta blockers. It would be helpful to know what specific rhythm you episode was. There are several options including going off all medicine all together or use of a relative drug with a different side effect profile. If the rhythm were to return, you could also possibly undergo an ablative procedure.
good luck
I don't know the answer, but in your situation, I'd get a second opinion from another cardiologist, in addition to the opinon you'll get here from the doctor.
That's got to be frustrating. I would definitely seek a second opinion, like was mentioned prior, preferably from an EP.