I'm not one to argue, but are you saying that by becoming all around healthier will not reduce your risk of heart disease whether you already have it or not? I find that hard to believe. If you have some form of heart condition/disease/weakness, becoming healthy on all fronts whether its low fat only, or fully changing your food intake to a balanced "diet" will reverse/slow down/stop your risks. A balanced diet is lower in fat, lower in carbs, and lower in basically everything other than MAYBE fructose if your fruit intake skyrockets.
Being healthy is being healthy any way you look at it. Health risks of all kinds deplete as you progress.
All that being said, maybe I read what your wrote wrong.