What Causes Arrhythmia Of Heart Along With Shortness Of Breath?

I have arrhythmia, and have developed extreme shortness of breath. I take a diuretic and a beta blocker (Carvedilol) 25 mg twice a day. Still the shortness of breath is extreme. Currently have a Holter monitor, the new digital 14 day unit. Potassium has been added to my regiment 20mg. daily. I also have started using a c-pap. Any Ideas that the doctors have overlooked.