A-fib with heart blockage

My father had triple bypass 15 years ago and was doing well up until a year ago.  He has been having chest pains and discomfort.  He had a catherization last Oct and they found some minor blockages they would treat with medication.  Altenolol was one.  In April 99 he landed in the hospital with A-fib.  They electro-cardio converted him three weeks later. On Friday last week he was in A-fib again.  They did a stress test on him yesterday and he had heart failure and was shocked back.  THey then did another catherization on him and discovered he has even more blockage than a year ago.  They put a stent in one of his arteries and are going to treat the rest of the blockage with medication because the blockage is in arteries too small to do anything else with.  As soon as the coumadin he was on is out of his system they are going to install a defibrillator.  Does he have any other options?  Also is he in danger of a stroke where they are going to stop the coumadin in order to put the fibrillator in?  I've been reading where he could be at danger if they stop the coumadin too soon.

[CCF CARDIO MD JMF]

The risk of going off coumadin is samll and your father will likely receive heparin to bridge him to the procedure if required.