Cardioversion success improve after conditioning program?

I was diagnosed with full time a-fib four years ago ( I am 39 and male )and was put on coumadin.  After two unsuccessful cardioversions ( held rythem for three days),  A holter moniter found that I had elevated heart rates (190s during walking) so I was put on beta blokers and dig, plus lipitor for borderline(210) colesteral.  Cardiolyte stress test and angiogram found no blocks or other problems.  It was about this time that I began a light running program, which became a serious running program  with me finishing my first marathon last May ( although slow, 4:45)  When I started my program,   my heart rate would hang around 200 to 210, and my cardiologist thought my night time heart rate was too slow(around 25).

  This past week , I put the monitor back on and found that it peaked at 175, with my resting (sitting on the couch) rate of 40.

So the questions are:

1)With the heart rate dropping, is there any evidence that a cardioversion might take better?

2)Is there  evidence that activities like marathons might cause someone with cronic (chronic) a-fib to suffer from CHF sooner than someone with a normal sinus rythem?
Or should I leave well enough alone because I really don't notice symptoms?
Thanks for your help.

[CCF-M.D.-RCJ]

wingtip,

Congratulations on running the marathon.
(1) I know of no evidence to indicate that the cardioversion would be more successful after aerobic training.

(2) Afib is not a known cause of CHF except for in patients who have undiagnosed tachycardia from the afib, then leading to a usually reversible cardiomyopathy.  I would encourage your activity as a way to prevent CHF.

Keep up the good work.