Occlusions greater than 70% should be medically treated...
stent if meds are ineffective. CABG for occlusions to large to
stent, location is not appropriate for stent implant, emergency, etc.
For more than 5 years I have known I have a completely blocked LAD. RCA 98% occluded stented, and circumflex 72% occluded. If have no symptoms with regular activities, but before going to the gym I take a nitrate pill and that prevents any chest pain, etc.
Hope that gives you some insight.