I take xanax 3 times per day right now for my panic.. and yes once it kicks in it does slow down your heart rate.
I agree with what Jerry_NJ said. It stands to reason, that since xanax is intended to reduce or relieve anxiety/panic symptoms during which our heart rate would likely be increased; then, I would assume that the heart rate would not be running as high once the xanax kicked in - due to a reduction in anxiety/panic.
Well, if the Xanax helps relieve anxiety, that could, I think slow the HR down. Are either of the other two medications beta blockers? If yes, they will slow your HR.
What is your rest HR, and what was it when it was higher?