The ACC/AHA classification of heart failure has four stages.

Stage A includes those at risk for heart failure, but who have not yet developed structural heart changes (diabetics, those with coronary disease, but no prior infarct).

Stage B includes individuals with structural heart disease, however no symptoms of heart failure have ever developed.

Stage C includes patients who have developed clinical heart failure.

Stage D are patients with refractory heart failure requiring advanced intervention (biventricular pacemakers, left ventricular assist device, or transplantation).

Note that the ACC/AHA classification is much different from the New York Heart Association (NYHA) functional class in that there is no moving backwards between stages. Once symptoms develop, stage C heart failure is present and stage B will never again be achieved. The NYHA classification, in contrast, can move between class I and class IV relative quickly as these are all designated based on symptoms alone.