The New York Heart Association (NYHA) Functional Classification provides a simple way of classifying heart disease (originally cardiac failure), useful for preoperative assessment. It places patients in one of four categories, based on how much they are limited during physical activity:

• Class I: patients with no limitation of activities; they suffer no symptoms from ordinary activities.
• Class II: patients with slight, mild limitation of activity; they are comfortable with rest or with mild exertion.
• Class III: patients with marked limitation of activity; they are comfortable only at rest.
• Class IV: patients who should be at complete rest, confined to bed or chair; any physical activity brings on discomfort and symptoms occur at rest.