In 1989, there was a lack of knowledge as to the relative efficacy of different treatment strategies to control asymptomatic cardiac ischemia. Given the estimated high prevalence of asymptomatic cardiac ischemia in patients with coronary heart disease and evidence of increased risk of untoward outcome, the public health problem was of sufficient magnitude to warrant a pilot study to determine to what extent asymptomatic ischemia could be controlled. If the pilot study demonstrated feasibility, a full-scale clinical trial would then be considered to evaluate the impact of effective treatment of asymptomatic ischemia on survival and cardiovascular morbidity in patients with coronary heart disease.