Hello. Welcome to hcm.
Let me explain the pathology first. Heart attack
occurs when bllod supply to heart stops leading to its failure. So less amount of blood goes to all parts of body. slowly lungs also get less blood and blood can go out causing edema. It can be managed by drugs but till the heart pumps properly,it breathing problem cannot get relieved. Normal heart output is 65 percent but for your father,it is less than half. Also as brain gets less blood,it will be less active. Even sedation will be given in hospital too. So he is very sleepy.
I advice you to wait till the drugs act. If the obstruction was acute,surgery would be a choice but as the heart is already damaged,its full return is questionable.
Hope he responds well to treatment and he recovers.
All the best