Your low heart rate is being taken care of with your pacer. Your AFib may be alleviated when they treat your thyroid problem as some thyroid problem exacerbate AFib. If this is not the case, there are BB (beta blocker) that can convert AFib to NSR as stated by Jerry above.
Jerry is right about the non-relationship between bradycardia and AFib... two separate issues. I had both so I had a pacer implanted but still have the AFib, although it is controlled through meds.
So how are you being treated?
ksig
It is my opinion that the AFib and low HR, bradycardia are not related. The HR problems that usually are associated with AFib are high HR and irregulary HR.
That said, you may feel better if the AFib can be halted...you'll also be safer as far as clot and stroke risk is concerned.
Some people convert from AFib to Normal Sinus Rhythm (NSR) with medications. I don't know the % but if your AFib is only occasional and has not been going on for years, and if your heart is structurally normal (i.e., you problems are all electrical) meds may be just what you need. Among the "softer" medications are the many Beta Blockers and Calcium Channel Blockers and the anti-arrhythmic drugs like Propafenone/Rhytmol and at the stronger level Flecinide. The group participating on this Community (Forum) have a lot of experience with those and other drugs to control/convert AFib. I have never been converted by medications alone, but I have some evidence that Propafenone has help hold me in NSR after an electrocardioversion.