He's very young to need this surgery & to have failed a stress test
1) stop smoking
2) exercise regularly
3) eat a heart healthy diet
As for the surgery, expect 5-7 days in the hospital. The first couple in ICU
. He likely won't be fed for a couple of days, until his intestines start working. When he goes home, he'll be tired for a month or so.
Good luck & hang in there!