The New York Heart Association Functional Classification distinguishes four categories of heart failure according to how much the patients are limited in their physical activity.

Category I: No limitation of physical activity. No undue fatigue, palpitation, or shortness of breath.

Category II: Slight limitation of physical activity. Comfortable at rest. Fatigue, palpitation, or shortness of breath at ordinary physical activity.

Category III: Marked limitation of physical activity. Comfortable at rest. Fatigue, palpitation, or shortness of breath at less than ordinary physical activity.

Category IV: Discomfort with any physical activity however slight. Symptoms of heart failure at rest. Increased discomfort whenever any physical activity is undertaken.