Objectives: This report from the Asymptomatic Cardiac Ischemia Pilot (ACIP) study examines differences in the magnitude of reduction of myocardial ischemia as determined by exercise treadmill testing in patients randomized to three different treatment strategies: angina-guided medical therapy, ischemia-guided medical therapy and coronary revascularization. Background: No prospective randomized clinical trials in patients with exercise electrocardiographic (ECG) abnormalities and asymptomatic cardiac ischemia on ambulatory ECG monitoring have compared the impact of different treatment strategies, including coronary revascularization, in terms of reducing myocardial ischemia. Methods: The ACIP exercise protocol was used. Exercise variables measured included final exercise stage; presence of exerciseinduced angina or ischemia; time to angina; time to 1-mm ST segment depression; number of exercise ECG leads with abnormalities; maximal depth of ST segment depression in any lead; sum of ST segment depression; ST/HR index; and rate-pressure product at time to angina, at time to 1-mm ST segment depression and at peak exertion. Results: Peak exercise time was increased by 0.5, 0.7 and 1.6 min in patients assigned to the angina-guided, ischemiaguided and coronary revascularization strategies, respectively, from the qualifying visit to the 12-week visit (p < 0.001). At the qualifying visit, the sum of exercise-induced ST segment depression was 9.4 ± 5.0 (mean ± SD), 9.6 ± 4.7 and 9.9 ± 5.5 mm (p = NS) in the three treatment strategies, respectively. At the 12-week visit, the sum of exercise-induced ST segment depression was 7.4 ± 5.7, 6.8 ± 5.3 and 5.6 ± 5.6 mm (p = 0.02) in the three treatment strategies, respectively. Each treatment strategy resulted in a significant reduction in all exercise-induced variables of myocardial ischemia measured at 12 weeks. Conclusions: Coronary revascularization significantly reduced the extent and frequency of exercise-induced myocardial ischemia compared with either medical strategy. The prognostic impact of these observations should be evaluated in a large-scale multicenter clinical trial. © 1995 American College of Cardiology.