atrial fibrillation and cardioversion

I've had atrial fibrillation for 3 years and have been diagnosed with sick sinus syndrome.   My cardiologist was unable to do an ablation because of the location.  I have been cardioverted three times.  I have been maintained on flecainide for almost 2 years, but recently had an episode.  I was cardioverted and my dose of flecainide has been increased from 200mg per day to 300mg per day.  Is there a maximum number of times that one can undergo a cardioversion before it begins to damage the heart?

[Jerry_NJ]

I assume you are talking about a electrocardioversion - i.e., electric shock.

I have had four of them, the better ones held me in NSR for about 1.5 years each, the last one lasted only one week.  My problem is my atrium chamber has been enlarged by a leaky mitral valve and it can not be converted...otherwise I would have continued to use the electrocardioversion every couple of years, no worry in my mind/knowledge about it damaging the heart in any way.