 Patients 21 years of age and older with coronary artery disease may be eligible for this study. Candidates will be screened with a medical history and physical examination, including a cardiovascular evaluation, and blood tests. The participants will be enrolled in a 2- to 3-month cardiac rehabilitation program that includes 24 to 36 60-minute sessions of exercise, plus instruction on lifestyle changes related to diet, stress management, and relaxation techniques. In addition, participants will undergo the following tests and procedures: 