Come to think of it, if Bill Clinton were to pass away before 2008, Hillary's chances of running for and winning the Presidency would be about nill.
First off, she would not be able to carry on in politics by herself, I don't believe, and I don't think the American public, including Democrats, would want to see an old spinster living alone in the White House.
I also forgot to mention that for non-emergent CABG cases, there is a host of other studies that should be done before the surgery, including carotid artery assessment and pulmonary function studies among others
Then, close to my heart, there is always the Anesthesiologist issue to deal with also (no pun intended)...