My Mother Is82 Yo With Moderate+ Alzheimers. She Has Spontaneously

My mother is82 yo with moderate+ Alzheimers. She has spontaneously become unconscious with no pulse requiring CPR & ambulance on 3 separate occasions. All cardiac exams, blood tests, etc. have come back negative for a problem. Is this a symptom of Alzheimer's ? Or what can I pursue. She cannot have MRI with a pacemaker.