
If your vet has identified a cause of the heart disease and this can be treated (such as removal of an over-active thyroid gland) the damage to the heart muscle might actually repair with time.
Unfortunately, it is unusual that the root cause can be treated so easily and in most cases long-term medication is needed to control the signs.
Sometimes your vet will recommend a special diet that may have low salt to reduce water retention. However some cats do not like these diets and will refuse to eat them. It is much more important that your cat eats than has any special food.