Family called into hospital, patient prospects?

Hi, my dad got a call from the hospital where my uncle has been under observation due to chest pain. Seems he took a turn for the worse and is undergoing emergency surgery. My dad is pretty broken up about it.

He had a stent procedure a month or two ago and seemed to be doing well until his chest pain started reoccuring, went back to hospital and was admitted for observation.

I was just wondering under what circumstances immediate family are requested to come to the hospital during a procedure, does he have any chance of recovery at all?

Im a bit out of the loop here until someone gives me a ring, good or bad news.