### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Hi, I`m Lee, a 41 year old male. Diagnosed with endocarditis(mild regurgetation) in 1991 with enlarged right atrium. Progressed to severe tricuspid regurgatation in 2000. In 2001 had tricuspid valve replaced with prostheric valve. Since surgery, I`ve been great, free from medication and led a active life with no symptoms(apart from odd chest pains & rapid heart beat once ot twice a year). Last computer heart scan was 2006 all normal. started to to feel mild breathlessness & tired in 2010. Computer scan in Feb 2010 revealed Heartbeat 125pm, severely enlarged right atriam, mild tricuspid regurgatation with atrial flutter/fib. I`m due for catheter ablation in September 2011 to cure atrial fib. My cardiologist thinks old scaring from previous surgery caused A Fib. My question is: could the A fib be caused by my severely enlarged right atrium causing abnormal electrical pathways. If so what is the correct possible cure,ABLATION or futher surgery of RIGHT ATRIAM REDUCTION? Will the ablation procedure reveal the cause of the A fib?Thank you,Lee

### output:

Hello, the precipitating cause for atrial fibrillation in your case would have been the scar of previous surgery. The pre disposing factor is the enlarged atrium. Generally medicine should be enough to treat and prevent future episodes of atrial fibrillation / flutter. However, ablation is a good option for someone who doesn't want to take medicine for the same. The success of ablation in your case would be best at 85 %. Yes the ablation will help to reveal the cause and Your doctor will try treating all the Chat Doctor.  No surgery to reduce the size is not a viable option. Regards 