What is the life expectancy of a 41 year old after coronary artery bypass, if they stick to medication and don't have co-morbidities?

I would look at how long all of his relatives lived and what they died of. Stop smoking is first thing. The lower his LDL the longer he will live. This can be lowered by Ornish Diet and/or meds. Your can go to several risk calculators online and enter his data which will predict risk of another heart issue over next 10 years. Ideally get BMI down to less than 25.Keep BP less than 120 systolic.