The first five years of the grant quantified the activity of myocardial ischemia in approximately 90 ambulatory patients with coronary artery disease out-of-hospital in order to: study the natural history of ischemia in relation to the occurrence of coronary events; examine the effects of all out-of-hospital active ischemia on prognosis; establish if monitoring of active ischemia provides information about the risk of coronary events apart from usual testing The longitudinal study characterized patients according to history, symptoms, risk factors, exercise testing for myocardial ischemia, and cardiac catheterization data. Serial 48-hour ambulatory monitoring of the electrocardiogram was performed on and off standard medication at baseline and at six month intervals. The frequency and duration of all active ischemia out-of-hospital were related in a multivariate analysis to symptoms, clinical and laboratory data, and to coronary events such as death, myocardial infarction, hospitalization for unstable angina, and need for revascularization. Patients were enrolled during the first two years and followed for two to four years.