Class I

No limitation of physical activity. Ordinary physical activity

does not cause undue breathlessness, fatigue, or palpitation

Class II

Slight limitation of physical activity.

Comfortable at rest, but ordinary physical activity results in undue breathlessness, fatigue, or palpitations.

Class III

Marked limitation of physical activity. Comfortable at rest, but less than ordinary activity results undue breathlessness, fatigue, or palpitations.

Class IV

Unable to carry on any physical activity without discomfort.

Symptoms at rest can be present. If any physical activity is undertaken, discomfort is increased.