I am on 5mg Bisoprolol and still after three weeks cannot get used to it so my doctor said to reduce the dose to 2.5mg.
My resting HR before taking the pills was about 95, on 5mg that is down to about 80 (before persistent Afib it was 58!). My concern is if I reduce the dosage then my resting HR will go up again. Am I correct in this assumption?
I'm not medically trained Beaky but I think the answer is yes because betablockers are prescribed to reduce heart rate and blood pressure. The normal heart rate range is between 60 and 100 bpm although for many, 100 bpm might be a bit high but it might be worth trying a reduced dose to see how your get on. There are alternatives, many here speak well of Nebivolol which is a different form of betablocker. Also, some prefer Calcium Channel Blockers such as Diltiazem but GP's are sometimes unwilling or unable to offer alternatives therefore you may need to consult an Electrophysiologist (EP)/Cardiologist.
As FJ states normal is between 60 and 100 and my local cardiology team state that they do not treat HR below 100. This game is all about trying different things I'm afraid.
I gather that bisoprolol is given only to help with symptoms rather than to help the arrhythmia itself; also, that its dosage response is not linear, so halving the dose will not halve its effect or side effects. I struggled with it as you are doing and even dropping to 1.25mg I wasn't well on it. Different people are differently affected by beta-blockers, that's my experience. I suspect a call to your GP is required and that he or she might well suggest halving the dose to see what that does.
Steve
HR will possibly increase, mine went from low 30s to high 90s when I stopped taking bisoprolol, but a few months after stopping my HR was in the high 50s and has remained at that for at least the last 2 years
Try the reduced dose and see how you feel. 5mg seems to be the standard starting dose for many doctors - I was put on that dose twice by hospital cardiologists here . After about 10 days the first time I felt so awful I did not want to live if it meant living like that and I told my GP. He said to reduce the dose to 2.5 mg. When I saw my own cardiologist he said I could gradually reduce that and come off in a couple of months. The second time I was put on after afib reared it's head in hospital after major surgery I was forearmed. I just took a quarter of the 5mg after I had gond back into NSR. Even on 1.25 mg I felt sluggish. I now take Nebivolol which is for me better. If you feel ok on the 2.5 mg you could ask to reduce further . There is no point in taking more of a drug than is needed to reduce your symptoms when treatment for afib is for QOL.
The NHS is run on two strategies for AFib. Rhythm or Rate control. In Scotland it is currently rate control. Check which path you are on. Medication is then administered to achieve the goal. Steady rhythm or controlled rate to parameter. Be careful about self messing about with med dose. As stated above it is not a linear graph. I started on 17.5mg Biso per day, I am now at 10mg but cannot go any lower. I have just gotten used to it. Also Bisoprolol is normally lined up with another medication. EG Digoxin which I take. Altering one can in turn alter the mix with the other. Possible problems then lie ahead. Seek a Cardiologist/EP advice on this. IMO
I would be surprised if you notice a big difference in your heart rate as long as you are still on Bisoprolol. Anticipate feeling a bit keyed up or anxious if you stop taking the tablet all together. I would suggest reducing over a couple of weeks and then cutting tablet in half then every other day.
76 years old with A F
apixaban and hematuria 
shortness of breath
3% Afib burden and proposed medication
