a functional classification to assess cardiovascular disability. Class I: patients with cardiac disease without limitation of physical activity. Ordinary activity does not cause symptoms. Class II: patients with cardiac disease with slight limitation of activity; comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea or angina. Class III: patients with cardiac disease producing marked limitation of activity: comfortable at rest. Less than ordinary physical activity causes symptoms. Class IV: patients with cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms may be present even at rest.