| Heart failure | Symptoms | Objective Assessment |
| Class I | No limitation of physical activities. Ordinary physical activities do not cause any symptom | No objective evidence of cardiovascular disease |
| Class II | Slight limitation of physical activities. Comfortable at rest. Ordinary physical activities may cause symptoms like fatigue, palpitation, dyspnea | Objective evidence of minimal cardiovascular disease |
| Class III | Marked limitation of physical activities. Comfortable at rest. Less than ordinary activities may cause symptoms like fatigue, palpitation, dyspnea | Objective evidence of moderately severe cardiovascular disease |
| Class IV | Inability to carry out any physical activities without discomfort. Symptoms of heart failure present even at rest | Objective evidence of severe cardiovascular disease |