The New york Heart Association (NYHA) functional class helps to classify patients based on their symptoms of heart failure.

Class I: No symptoms of heart failure
Class II: Symptoms of heart failure with moderate exertion such as ambulating 2 blocks or 2 flights of stairs
Class III: Symptoms of heart failure with minimal exertion such as ambulating 1 block or 1 flight of stairs, but no symptoms at rest
Class IV:  Symptoms of heart failure at rest

Note that the NYHA functional class differs from the ACC/AHA heart failure classification system in that the former allows movement from one class to the other while the ACC/AHA classification does not (see below).