Hi and welcome to HCM.
i am sorry about your uncle and it sounds like very serious and life threatening condition which is to be expected in massive heart attack
. i cant say what brain mas is but it can be tumors, intracranial bleeding or brain insult. In every case this is not good sign. Why isnt he awake? probably because he has acute brain damage
and his brain suffered ischemia
during his heart attack. So you need to be patient but prognosis isnt well.
Wish you good health.