A lot of that depends on your father and his overall condition. No one can give you a straight answer. Have you talked to anyone else about this?
I just posted and it disappeared. Grrr.
I don't know what your Dad's chances are because so much depends on the condition of his heart, what damage is done. My Dad had 3 heart attacks (different than cardiac arrest) but he lived for more than 20 years after his first attack and actually passed away from cancer. So you never know.
Talk to the doctors. They know much more about your Dad's condition and can explain what they can do to help.