Class I: “Ordinary activity does not cause angina.” Angina with strenuous or rapid or prolonged exertion only.
Class II: “Slight limitation of ordinary activity.” Angina on walking or climbing stairs rapidly, walking uphill or exertion after meals, in cold weather, when under emotional stress, or only during the first few hours after awakening.
Class III: “Marked limitation of ordinary activity.” Angina on walking 1-2 blocks (100 – 200 m) on the level or one flight of stairs at a normal pace under normal conditions.
Class IV: “Inability to carry out any physical activity without discomfort” or “angina at rest”