What Are The Chances Of Requiring A Third Electrical Cardioversion?

I have severe dilated left valve and moderate dilated right valve w/ regurgitation, hx of stroke on 09/2013. Dx w/ AFib on on 06/2014 have had 2 electro cardioversions, most recently on 03/06/14. Im back in AFib after my 1 month check up. Should I be concerned with another attempt of a 3rd cardioversion? Its as if im playing musical chairs