How long will nerve damage pain last after a 5-way bypass? it has been 17 months since the surgey

That's long: It depends what kind of nerve damage you're referring to. The area from which the left internal mammary artery was dissected (corresponding to the left side of your sternum) remains painful for 1-2 years and then often becomes numb. A paralyzed phrenic nerve will never regenerate. Post op stroke recovery is variable depending on extent. Generally, at 17 months, you may not see much further change.