Medication is always best if the patient is not in a life threatening situation. Cholesterol medications have shown in studies to help reduce cholesterol levels and help reduce some blockage in the arteries. Make sure that she is taking her medications as prescribed by her doctor. If she can eliminate red meat from her diet that would be best. She should eat organic fresh vegetables and fruits mostly. Stay away from any canned vegetables as they contain a lot of salt. Stay away from fast food and processed foods. Brown rice is good to eat and filling. Adding honey helps if she does not like the taste. Her current heart medication may have the side effect of making her feel tired, but she still needs to take them. If she has inflammation in her arteries this could cause the cholesterol to stick and buildup. If she has arthritis, then she most likely has inflammation. Aspirin at 81mg helps with the inflammation and she may already be taking the aspirin daily. If not, ask her doctor if she should. Procedures and surgeries have risk, especially if the person is older.
Medication, stent implants and CABG treat symptoms (chest pain, shortness of breath, muscle fatigue, etc) and does not cure the disease.
The COURAGE study has concluded that the mode of treatment (medication, implants, CABG) has no effect on longivity. AAC/AHA guidelines for treatment of CAD for an occlusion less than 70 not to be treated unless symptoms prevail. 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. Your mother's doctor is following the appropriate protocol...no comment on the efficacy of the CABG, but statistics show there are unnecessary implants and CABG operations where medication could have been the appropriate treatment.