I'm taking Bisoprolol and it took 2 months of fiddling with the dose to get it right. I joined an A.Fib Support Group to get more info about the condition generally, and many Group Members had had problems with Bisoprolol. I realised that side effects were being expected when the pharmacist rang me twice to see how I was getting on.
I rang the British Heart Foundation when I was having a challenging time with Bisoprolol, and she suggested taking the prescribed dose but splitting it, half in the morning and half in the evening. I am only on a low dose but I have a medical history of bad reactions to almost any medication. Now I take 1.25 mg. with my breakfast (and also an anticoagulant), and another 1.25mg with my evening meal. I checked with a doctor first.
I do get breathless but I also have asthma so it's hard to know what is causing what.
There are alternative beta blockers if a split dose doesn't work for you.