What Causes Sudden Shortness Of Breath In An Obese Person?

Question is about my friend. He is 40, obese. Just 3 weeks ago he started having shortness of breath. While overweight he had no problems up until that point functioning (would work out on treadmills, lift light weights) The breathlessness episodes increased. He had previous fluid build up in is legs/feet and abdomen, and the shortness of breathe is likely fluid (ie: cardiac asthma). So far they are treating it as pre-asthmatic , but due to waking up in the night gasping for air, he is going to the doctor tomorrow to get his heart examined. It is likely congestive heart failure, my question is what his prognosis could be, in terms of years left and level of functioning,. He has/had been eating better and exercising prior and making great progress. How many years could he live, for example, would he be able to reach 70?, 60? 50? We are very worried and concerned. Thank you