I do know his heart was weakened due to cardiac myopathy. He turned purple in the middle of the night, and was out cold for a week or so before he woke up.
It may have been caused by drinking alcohol. I really don't know.
My father did not need a fibrillator, he was given medications. As far as your father I would not know what can be done going forward if they do not know what caused it to occur in the first place.
I am sure there are many people on this site that will be able to offer more detailed information.
I don't know what caused it. Your father had it too. Did they insert a fibrillator?
Do they know what caused it? My father had it but it was caused by alcohol, once he stopped drinking it resolved.