Should I Continue Bisoprolol If My Pulse Stays Below Normal Even After Activity While Having Atrial Fibrillation?

Hi I am a 73 year old woman who had a pacemaker fitted in 2015 as my pulse was dropping to around 30bpm during my sleeping hours. Lasy year I was diagnosed with AF and was put on beta blockers (7.5 bisoprolol per day). My pulse rate now never varies above 50bpm,even after walking for 40 mins. Do I still need to take bisoprolol.has my pulse is being held down to 50bpm. Thank you.