I think this may boil down to how confident you are with your cardiologist and do you feel he has done everything he can to help you with your heart issues.

I think if I was in your shoes, I would be getting a second opinion just to have the peace of mind that I've done all I can to help myself. If the second cardiologist agrees with your cardiologist, then you can probably be confident that a bypass isn't possible. However, if they say it IS possible, then you have a choice to make.

I couldn't find a lot of reviews on cardiologists in your area. I'm not sure if you're able to drive roughly 3 hours to North Kansas City. If so, here are two cardiologists that have good reviews (found via Google maps):

Drew S. Allen, D.O., FACC
https://www.nkch.org/find-a-provider/profile/drew-s-allen-cardiovascular-disease
Michael W. Farrar, M.D., FACC, FASE
https://www.nkch.org/find-a-provider/profile/michael-w-farrar-cardiovascular-disease
Here's the address for both cardiologists:

2790 Clay Edwards Dr #520, North Kansas City, MO 64116

Best of luck to you.