Ischemia can lead to myocardial necrosis, arrhythmias and death. Current practice suggests that asymptomatic or silent myocardial ischemia be treated as though it were symptomatic ischemia. This practice is associated with a growing trend of more frequent use of electrocardiographic monitoring, more complex therapeutic drug regimens and more frequent use of revascularization. However, there is no adequate study of the efficacy and safety of alternative therapeutic approaches to the treatment of asymptomatic myocardial ischemia. Therefore, the National Heart, Lung, and Blood Institute has planned the Asymptomatic Cardiac Ischemia Pilot (ACIP) study. The ACIP study is a multicenter international pilot trial to determine the efficacy and safety of angina-directed medical therapy, angina plus ambulatory electrocardiographic-directed medical therapy and revascularization. The treatment of asymptomatic cardiac ischemia is double-blind and placebo-controlled. The primary end point is elimination of ischemia on the 48-hour electrocardiogram at 12 weeks. Patients will be followed-up for at least 1 year. Secondary analyses will include comparisons of the 2 medical regimens, amounts of medicine taken, and exercise versus electrocardiographic results. Eleven clinical units are recruiting 600 patients with coronary anatomy suitable for revascularization, a positive exercise stress test, and 1 or more asymptomatic ischemic episodes on the 48-hours electrocardiogram. Patients are stratified by center, symptom status and previous coronary surgery. If warranted by the pilot study results, a full-scale trial will be considered to determine whether amelioration of asymptomatic ischemia improves survival and reduces cardiovascular morbidity.