Patients with heart disease should be aware of their cardiac functional status. The current evaluation of cardiac function is based on a grading scheme proposed by the New York Heart Association (NYHA) in 1928, which is mainly based on the patient’s conscious activity ability divided into four classes: Class I: Patients with heart disease, but the amount of activity is not restricted, and the usual general activity does not cause fatigue, palpitations, dyspnea or angina pectoris. Grade II: Patients with heart disease are mildly restricted in physical activity and have no conscious symptoms at rest, but fatigue, palpitations, dyspnea or angina pectoris can occur under general physical activity. Grade III: Patients with heart disease are significantly limited in physical activity, and less than usual general activities can cause the above symptoms. Grade IV: Heart disease patients are unable to engage in any physical activity. The symptoms of heart failure appear at rest and worsen after physical activity. The heart function classification reflects to a certain extent the severity of the patient’s heart disease. Patients can initially determine their heart function status according to their symptoms, so that they can limit their activities according to their heart function status, so as not to increase the burden on the heart and cause heart failure to occur.