After heart attack why do people spend time in hospital?

My dad has a heart attack and he needs to be hospitalized. He got to the hospital just in time unconsious, he was revived, sent into surgery. It seems he is recovering because he moves, opens his eyes and knows who we are, plus fallows commands! good sign right? Howver we're waiting for him to recupurate, he's gping through pain with all these tubes and cables on him. What are we waiting for..I know its something but I don't know what exactly. He didn't suffer brain famage we can see that with a scan.. Are we sedating him meanwhile his heart heals? What can be going on? Please help, thanks!