Thanks a ton for your information
I was in a similar situation in 2007 where medication was advised because the left artery was fed by collateral vessels. Unfortunately, my collaterals were not sufficient for much exertion, so I had to opt for bypass.
It depends on symptoms and quality of life. If your husband can do what he needs to for a normal quality of life (with or without meds) then there is no need for surgery. If surgery is required, then there will be another question considered, 'can bypass produce a better feed than the collaterals are'. If not, then bypass will be rejected. The collaterals are coming from another major vessel, the Lcx and this vessel, thank goodness, has no disease. This means of course that there's no way for the natural bypass to be cut off. Personally, I would leave everything as it is if possible. If you are not sure what collaterals are, they are small to medium sized vessels which open up to act as natural bypasses if a blockage forms. They don't open for everyone, but for the majority they do. It's natures way of keeping the heart muscle alive.