Left Main Heart Disease

My husband recently had a heart attack.  Age 58, active, not overweight, an athlete, etc.  The actual attack occurred in the right artery, and they put in a stent.  However, they found that his left main descending artery is 99% blocked and they said it is severely deteriorated, making him not a good candidate for a stent in that artery or bypass surgery.  They are trying meds, and hoping that with the meds and a diet low in bad fats, rehab, etc., he will not need a procedure.  They think he has had heart disease for many, many years without knowing it, since his body has developed "collaterals."
We are still learning more about is condition and will know more after his stress test at 6 mo.  An "echo" taken after his heart attack has shown some damage in both the right and left sides--not sure yet how much permanent.  We are stunned by this news and coping with it.  

I don't know that much about heart disease, so I am trying to learn.  Some of what I have read on the internet about diseased left main arteries is pretty scary.  We are together at all of his appointments, so we are informed as much as possible about the findings.  He is not a person who asks many questions.  There are some questions that I would like to ask, but don't want to do so since it might be upsetting to him.  I would like to know more about his prognosis.  I am a person who would rather know more about what we are dealing with -- it helps me cope and make decisions if I have more information.  Any feedback would be appreciated.  Thanks.