Congestive heart failure -- low ejection fraction?

What is the lowest ejection fraction a person can have and survive? My husband has an ejection fraction of 12 (as well as COPD). I know this is a question for his doctor, however, I have not been able to get a straight answer, so any insight would be most welcome. I am trying to figure out whether this is the final stage and if so, how much longer he has to live and how people with congestive heart failure typically die, just wasting away or suddenly and unexpectedly.