How successful is heart bypass surgery?

I cannot give actual percentages, but the success rate is very high. I know several people who have had by-pass surgery, one of whom had a quadruple bypass and the others triple bypass operations. All of them were extremely ill before surgery. One, in fact, had suffered a heart attack that was so bad that it was touch-and-go for quite a while. One is now running marathons, the rest of the triple bypass guys are all active and well, and the quadruple bypass guy (who had the surgery around 20 years ago) is still extremely active, and is still playing Golf at the age of 88.