Coronary artery disease is quite common, and physicians often are asked about the work capacity of patients with coronary disease; less commonly are physicians asked to rate the patient's permanent impairment. In such cases, Chapter 6, Cardiovascular System, of the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) is used to rate impairment. The AMA Guides directs the physician who is rating impairment to place the individual in one of four classes of impairment. Class 1 impairment is rarely used because patients often have neither significant lesions nor a history of angina. The likelihood of disease progression may qualify these individuals as impaired even in the absence of symptoms. Patients with Class 2 impairment have no symptoms even with moderately heavy activity, and moderate dietary adjustment or medication is required to prevent symptoms. Class 3 impairment describes individuals who have symptoms of congestive heart failure or angina with moderately heavy activity. According to the AMA Guides criteria, patients in Class 3 would qualify for US Social Security benefits. Class 4 impairment describes individuals who have symptoms during ordinary activity and should have signs or laboratory evidence of cardiac enlargement and abnormal ventricular function. For each class, the AMA Guides describes a range of impairment ratings and provides examples.