Clinically there is no such thing as Heart Failure Class IV. The American College of Cardiology categorizes the severity of heart failure into four classes, and Heart Function Class IV is one of them. The severity of heart failure in clinical practice is judged according to the cardiac function class, and the higher the class, the more severe the heart failure. Cardiac function class IV is the most severe one, which means that people with heart disease cannot engage in any physical activities, and even in the resting state, they will have heart failure symptoms. Heart function is a pathophysiologic concept, heart failure is a clinical concept, heart insufficiency compensation stage can not have any clinical manifestations, decompensation stage will appear heart failure symptoms, so heart failure is the late stage of heart insufficiency. Heart failure is a later stage of cardiac insufficiency. Cardiac function grade 4 is already the decompensated stage of cardiac insufficiency. If there is any abnormality, it is recommended to consult a doctor in time.