You don't want to alter your lifestyle, and you don't want to have the bypass operation? Artski, I think those are your only two choices, other than to do nothing and wait for nature to take its course. Possibly you could life a long life by doing nothing, because you never know. You could be one of those unusual people who manage to live for the next 20 years with a 90% blockage in the LAD. But if you don't want to just wait for the other shoe to drop, then pick an assertive path. With no symptoms, I personally would want to try exercise and diet, for at least a while. You have baseline measurements on record, so you will be able to tell in the future if your disease is progressing. If the arteries get any worse, you can decide to have surgery later. Some people would feel differently from me and would want to go ahead and make a clear channel for the blood to flow through as soon as possible. Your relatively young age, I think, does weigh on the side of going ahead and doing the operation. In any case, it's not an either/or proposition. If you choose to have bypass surgery, you still need to live a healthy lifestyle. The surgery doesn't take away your original risk factors. You got a wake-up call, and you have a chance to take care of yourself. Good luck.