There are four classes of heart failure as defined by the New York Heart Association (NYHA) and published by the Heart Failure Society of America (HFSA). These classes range from Class I (mild) to Class IV (severe). These classes can be also be found at abouthf.org, a heart failure education site created by HFSA.

Class I (Mild)

No limitation of physical activity. Ordinary physical activity does not cause undue fatigue, palpitation or dyspnea (shortness of breath).

Class II (Mild)

Slight limitation of physical activity. Comfortable at rest, but ordinary physical activity results in fatigue, palpitation or dyspnea.

Class III (Moderate)

Marked limitation of physical activity. Comfortable at rest, but less than ordinary activity causes fatigue, palpitation or dyspnea.

Class IV (Severe)

Unable to carry out any physical activity without discomfort. Symptoms of cardiac insufficiency at rest. If any physical activity is undertaken, discomfort is increased.

© 2002 HFSA, Inc.