My 67 Year Old Brother Who Had Cabg 20yrs Ago

my 67 year old brother who had cabg 20yrs ago and now he has another blockage on the same artery . His Bp is still not stable at this point , what is the risk of him going for another cabg. He had Triple bypass 20 yrs ago and now the angiogram showed he has 5 or 6 blood vessels occluded.