On an overall basis, I think you will feel better once you get the OSA treated. In terms of your biking stamina I can't help but think it willl help. However, in terms of the atrial fibrillation.......it may always impair your overall cardiac performance. (Remember, you no longer have a coordinated cardiac ejection of blood between your atrium and ventricle and thus it does affect your overall cardiac output physiology during excercise).