Reports of unsuspected, frequent and prolonged episodes of asymptomatic ST depression (ASTD) raised important issues for the evaluation and treatment of coronary disease. The traditional role of angina as the best indicator of myocardial ischemia had to be reevaluated, since several studies had shown that ASTD was much more frequent than symptomatic ischemia in many patients with coronary disease. If ASTD reflected clinically meaningful ischemia, then overt angina represented only 25 percent of the total ischemic burden. Moreover, incomplete data suggested that an increased and clinically unsuspected risk might be conferred on a patient with frequent episodes of ASTD. In 1988, studies were already in progress to find the most effective drug for treating ASTD. If no increased risk was associated with asymptomatic myocardial ischemia, there was little value in pursuing further investigations into its detection and therapy. But if the risk was increased, the detection and treatment of asymptomatic as well as symptomatic myocardial ischemia might completely alter therapy and the outlook for patients with coronary disease. The information in 1988 on the increased risk of ASTD was unfortunately scattered and sparse.