Hi Jim!
Are they telling her/you that the blockage is in a small vessel?, or that her vessels are too small?
I've had 3 major left coronary arteries bypassed, but I still have several small arteries that are plain and simple, too small to get a stent in and the thought process is that they will grow their own natural bypasses. I don't think I've ever had a Dr. tell me to wait til a part of my heart dies to feel better, though I suppose in reality that could happen, if the tiny blood vessels don't make their own bypasses.
One of the ways that they do this, is to give you statins to take. Then, Tammy watches her diet and keeps it low in cholesterol and fat, but she also needs to get up and move and exercise!! When you force that blood to move around and back up through those small blood vessels, that's when they actually try to start making their own bypasses!!
So basically, her main coronary arteries are open?? If that's the case and she has small vessel disease, that could be what's causing her all this pain! I have that as well. I wear a .4 mg. nitro patch for the angina pain, and knock on wood, it seems to be helping. But there is nothing that they can do. She may be a candidate for a therapy called EECP "Enhanced External Counterpulsation". It's where they put cuffs on your legs and (like blood pressure cuffs) as one cuff blows up and pushes on the leg to help the blood flow, the other goes down and so on...Take a look at the site below and it'll give you more details.
Best wishes and tell her hello!! Hugs, Teri 
http://www.clevelandclinic.org/heartcenter/pub/guide/disease/cad/eecp.htm?index=10476