82 yoM, Pradaxa (Afib) til 7/8, when pain, small gangrene 5th toe. Now much worse. CABG, dementia, uses walker. Arteriogram/surg possible before 7/15?

Unclear question. certainly consulting current treating physicians about surgery on the toe makes sense. The things that increase risk of heart disease and need for CABG all increase likelihood of dementia. Major surgeries like a CABG can cause, worsen and/or make cognitive impairment and dementia more apparent. Palliative care and symptom management may be a preferred approach.
Possible. Would depend on results of presurgical testing.
Arterial noninvasive. The 5th toe gangrene could be caused by an embolus or from severe peripheral vascular disease. To make that determination easily the patient needs an arterial noninvasive study. If pt has PVD, then arteriogram and revascularization is appropriate and sooner rather than later.