CDK43, it is very common, and I mean about 75% of the time, that a patient undergoing CA is in AF or flutter while the procedure gets underway. This is actually not a hindrance, and if the heart is in NSR during the procedure, the EP will 'challenge' the heart when he/she thinks that the isolation is complete to see if he/she is right. They will inject you with isoproterenol to stimulate the heart and make it go into AF if it CAN GO into AF. Then, they inject you with adenosine to slow the heart and see what the rhythm looks like on the scope to find hidden flutter. They won't release you from the surgery until they firmly establish that your spurious signals are truly isolated. Note that this doesn't mean the CA won't fail...they do. Happened to me and many thousands of others. After a few months, you should be offered another attempt, and the second CA's run about 80% success. One thing each reader needs to accept is that AF won't kill you. If left uncontrolled for a long time, yes, the heart will weaken and will 'remodel' itself to make treatment extremely difficult. But over several months of flutter or AF, you aren't likely to suffer irreversible harm. Also, there is empirical evidence that the atrium will 'revert' back to its original condition prior to the development of AF. Not fully, but mostly, or largely, and this is a hopeful thing that a corrected rhythm is the best you should hope for.