Well there are three types of acute heart problems which people commonly get confused and I am not sure which one you have reading your description.
1. Heart attack
2. Cardiac Arrest
3. Heart Failure
True heart failure (or CCF - congestive cardiac failure) is a heart condition which affects the pumping ability of the heart. With this condition there are a number medications which can control the symptoms and aid with volume and pumping action of the heart. The only 'cure' is a total cardiac transplant or implantation
of an artifical heart.
Obesity is closely linked with morbidity in cardiac problems.
Talk to your GP or cardiologist. If you do have heart failure you should have a heart failure specialist nurse who are a great source of support and advice. Talking things through with them should answer your questions more accurately than on here where we dont have clinical details, and should address and deal with your anxieties.
Hope this helps xx