Like Englishman, I inherited mitral valve prolapse and its accompanying a-fib*. My valve was repaired - reinforced with a plastc ring, and the a-fib took two sessions of catheter ablation to finally clear (after the first cath on the left nodes I was left with an a-flutter - better than a-fib but not normal) the second catheter ablation was on the right side, and that did the trick). Unlike Englishman, I am still fairly sedentary.
*I was also diagnosed with sleep apnea. I havn't used my CPAP since I came home from the hosital following my heart surgery. If YOU have sleep apnea - periodic cessation of breathing while you are asleep, PLEASE seek treatment of the apnea (a CPAP) and, if you can, go further to get the underlying cause of the apnea resolved. DO NOT rely on what your CPAP techs and their RNs tell you; they have a vested interest in keeping you on CPAP - they SELL YOU continuing supplies and service. I asked the RN I was working with if she ever had someone recover to the point of not needing the CPAP any longer and she said no. To me the goal of medicine is RECOVERY (healing) not maintaining the status quo. You have to participate in your healing by being your own best medical advocate.