Tabby is a female cat and is 11years old.My cat was overweight about 6 months ago. She was put on perscription diet food by the vet. She lost weight and was back to a healthy weight. She always had some kind of snoring problem or congestion in her nose. Recently, she passed away. Luckily I wasn’t there to see what happened. My brother saw it and said she might have had a heart attack and died instantly. Is there some kind of diagnosis or treatment that I could have prevented?…. I just cant get over it.