Well 70% isn't quite as bad as it sounds. Arteries are larger than they need to be anyway, and she still has a 30% flow which may give some symptoms under exertion but medication should be able to handle this. As for the circumflex blockage, it could be worth pursuing other hospital/cardiologist opinions. I had a total blockage in my LAD, which three renown heart hospitals in the UK said was impossible to treat. A bypass failed. It took 2 years, but a research hospital in London said they could do the procedure and this was due to the many number of years experience of the cardiologist. There are some important factors to take into account before making any kind of decision. If the artery is 100% blocked, then there could be dead heart muscle which means there's no point in any further intervention, heart muscle once dead, remains dead. I was lucky because tiny vessels called collaterals opened to give a small feed to the muscle, enough to keep it alive. So you really need a clear and accurate assessment on this first. Secondly, the symptoms of the patients are obviously important in your decision. If there are no real uncontrollable symptoms from medication, then it's probably wise not to risk any further procedure. Medication didn't help my symptoms which is another reason I went for it. Lastly you need to understand the risks involved. A catheter wire has to be passed right through the blockage and the ends of the blockage will be very hard. If too hard, or the thickness of the hard 'skin' is too great, the wire will not penetrate. There is a chance it can shoot sideways and pierce the artery wall, causing an internal bleed. Once pierced, the entire vessel can sometimes just tear open and this will be game over. If the wire goes through the blockage then the biggest risk is over. Ask cardiologist lots of questions, such as why they feel they cannot do the procedure, is it due to their lack of experience. If so, you don't want this cardiologist doing the procedure anyway.
So, hopefully a few things for you to think about. Lifestyle changes, such as healthy diet, cholesterol control, blood pressure control, avoiding stressful situations can all aid in a comfortable life and stop progression of the disease. So, I urge you to think carefully, mainly based on the current symptoms and how well medication helps.