This not something that is likely to kill him. My mom had the same procedure done this past Monday. She has so many stents, I think they were putting a stent in a stent. She went in on Monday and was home on Tuesday.
She is 79 and had her first heart attack and quadruple heart by-pass in 1990 when she was 59. She has had tons of procedures like this in those 20 years. Last year she had huge by-pass surgery on both her legs.
They can do amazing things, my mom's parents died of cardiovascular issues in their early 60's and that probably would have been my mom's fate as well, but we have the best health care in the world in this country. Due to the research, the pharmaceuticals (evil big pharma!!) and wonderful procedures, she is still with us 20 years later and she still leads a pretty active life for a woman her age.
I bet President Clinton will be fine and probably back working by next week.