Functional class	Limitation of physical activity
Class I	No limitation of activity. Ordinary activity does not cause undue fatigue, palpitation, dyspnea or anginal pain.
Class II	Slight limitations of physical activity. Patient is comfortable at rest. Ordinary activity results in fatigue, palpitation, dyspnea or anginal pain.
Class III	Marked limitation of physical activity. Patient is comfortable at rest, but less than ordinary activity causes fatigue, palpitation, dyspnea or anginal pain.
Class IV	Inability to carry out physical activity without discomfort. Symptoms of congestive heart failure may be present, even at rest. Increased discomfort with any physical activity.