Afib and atenolol

I have been in Afib and my dosage of atenolol was just rasied from 25mg to 50mg. While it does seem to keep me out of Afib, I am somewhat depressed and, worse, can hardly walk I feel so sluggish. What are the dangers of staying in Afib (I had a TIA in March and am on coumadin).

[Jerry_NJ]

I am in permanent AFib and take only a beta blocker (Metoprolol 100 mg) to keep my HR below 100, resting is usually in the 80s, and coumadin (warfarin) to guard against blood clot formation.

As I have very mild symptoms my cardiologist and the consulted EP will not do an ablation (I no longer can hold sinus rhythm from electrocardioversions) as the risk isn't justified.  Said another way, my life expectancy is not improved by gaining NSR.  Or better said, AFib is not life threatening... but I do have to walk-the-line on my clotting control.