Welcome to HealingWell and I am so sorry about your brother.
Are you saying his Ejection Fraction is 20 %. Normal would be 50% - 60% +/- 5%
Does he have intra-aortic balloon pump (IABP) in to help his cardiac output?
The dye used for angios may have an effect on his kidneys but will they shut them down forever, I do not know. This is where you talk to his cardiologist and pray. We will be praying with you.
Let me tell you a good story that may give you hope.
My sister was dx in August with ovarian cancer..........her CA 125 cancer marker on admit to the hospital was 22,000. She had her last chemo today and her CA125 cancer marker was down to 35 and should drop even more once todays chemo kicks in. Miracles do happen. She was in the ICU on a ventilator is full system shut down when we flew her to the U of MN. We are now planning surgery for January. She has been here in MN for 112 days.............lives in North Dakota :)
Don't give up hope and know I am her for you.
Bless you and your brother. I hope you keep us posted and know we are here to support you.