Why did my cat die? i have a lot of questions. please read.please answer if you can.?

last year,at about the end of july, we found him hiding in the cattails on the side of the highway miles from any houses,or for that matter,any buildings at all. we supposed somebody had dropped the little kitten off . we didn`t find any other kittens with him. we took him to the vet who told us he was probably about four weeks old and he appeared to be a bengal (if you know what that is, it`s a pretty new breed) . he seemed pretty healthy, but after a while we noticed if you listened to him breathe he sounded like he was wheezing. the vet said nothing of that fact. we kept him . the skinny kitten soon grew to a healthy weight , but after a few months developed a moderately large belly . we attributed this to fat, but the rest of him seemed to be normal,if not slightly skinny. could it have been something else? he had an incredibly human personality and talked. not just phrases, but long sentences. he`d often hold conversations or get into arguments with us. he loved to play with our daushund or cuddle with our other cat.he was a fulltime indoor cat.today we took him to the vet to get neutered and declawed. a couple hours later they called to say our kitty had died. they said he was waking up after the surgery and they took him off the oxygen and his heart just stopped. the vet examined his body and found he had a very enlarged heart. was there any way we could have prevented his death? was there any way we could have known (signs, symptoms, etc.)? why did he die then as opposed to at home? any other information? thank you very much if you can answer any of my questions. i miss my baby kitty.