"I'm Ready"

It's what my grandfather shouted before he had his third heart attack last night. And now he's in a coma. He is the first person that I know of/am personally close to (related to) who is in coma. I am scared. Actually, I am beyond that. I am terrified. As soon as I got off the phone with my mother a few minutes ago, I began to shake and shed a few tears. Most people would see this as uncaring, but this is something that I rarely do, cry let alone feel completely torn about something and be visibly upset about it. I wish that there was something that I could do. I asked my mother what the doctors said about his being in a coma and told me that they said to just pray. The fact that the only thing that a doctor can say about something like this is pray is just...I don't even know what. I'm going to pray and hope that everything will be alright, but this is his third heart attack, and one gets to the point where they have to start viewing things realisitically. I don't know what to do. Did my grandfather mean when he said "I'm ready" that he was ready to leave this world? My mother thinks so, and I think that I do too. But I'm not ready.