It's unlikely to be a hoax. This is entirely within the realms of medical possibility as so far as I understand.
When a person stops breathing then parts of the brain start to die from lack of oxygen. This is very well known and reasonably well understood, and most people even know the "3 minutes without oxygen until the brain starts dying off" thing.
What people tend to forget is that when somebody goes down with a heart attack then even if you have a First Aider nearby it tends to take longer than 3 minutes to get them there. Consider this as a sequence of events:-
1) Person collapses and stays lying on the floor
2) People waste 30 seconds to a minute asking the unconcious body if they are ok.
3) People start thinking about calling 999.
4) Somebody discovers that the ambulance is going to take 15-30 minutes and the ambulance helldesk asks if you have a First Aider in the area and if somebody has gone to find one.
5) Somebody goes off to find a first aider
6) The first aider has a worse experiance than a first line helldesk trying to get "WHAT" (somebody collapsed) and "WHERE" (where I need to go) out of an incoherent if not outright hysterical messanger.
7) The First Aider takes a detour to the accident via a First Aid kit (because resusication marks are sort of mandatory when doing mouth to mouth, unless you are totally unconcerned with the possibility of picking up nasty infectious diseases that you could then also pass to your partner etc)
8) The First Aider arrives and applies CPR/AV and stabilises the casualty.
. . . How long did that take?
Betcha it's over 3 minutes so brain damage will have been taken to some extent, which may or may not be reversible. I have been the First Aider in this situation twice, and I do my best not to consider both how much brain damage the person has taken and the survival rates for people who have been resusicated.
My knowledge suggests to me that this sort of treatment is not likely to work a matter of days or weeks after brain deaths, but minutes or hours at the outside. It seem to be more probable to me that this is a treatment for people who were just over the brink after a slightly late resusication than doing a frankenstien.