What are the criteria for classification of cardiac insufficiency?

Cardiac insufficiency is classified into four levels according to the American College of Cardiology. Level 1 refers to patients with underlying heart disease, but normal activities do not cause such symptoms as palpitation and chest tightness. Level 2 refers to normal physical activity, patients will show palpitation, chest tightness, breathing difficulties symptoms. The fourth level is the most serious, that is, the patient does not do any activity, even when resting, he will show symptoms of palpitation, chest tightness and difficulty breathing.