Class I
No limitations. Ordinary physical activity does not cause undue fatigue, dyspnoea or palpitations (asymptomatic left ventricular dysfunction).
Class II
Slight limitation of physical activity. Ordinary physical activity results in fatigue, palpitation, dyspnoea or angina pectoris (mild chronic heart failure).
Class III
Marked limitation of physical activity. Less than ordinary physical activity leads to symptoms (moderate chronic heart failure).
Class IV
Unable to carry on any physical activity without discomfort. Symptoms of chronic heart failure present at rest (severe chronic heart failure).
