Be careful with stopping BBs. Some people have had heart attacks when they have stopped them. I have had SVTs since I was 18 and it seems that they occur more when I am stressed and when the anxiety is at its highest. I was even having them while on a BB. I was on Verapamil and now Cartia. They switched me from Verapamil after I had an episode after 5 years of none. The I was on cartia and had 3 in 5 months. I have not had one now since June, and that is when I went on Xanax and saw a therapist. I had every cardio test in the book and all showed nothing. I think that stress and anxiety causes the SVTs and the more I think and read about it I believe it.
Just be careful with stopping BBs cold because it can have adverse reactions.

good luck,
Lyl