Background: Electrocardiographic (ECG) monitored outpatient cardiac rehabilitation (OP-CR) is routinely performed following a variety of cardiovascular procedures and conditions. Objective: The aim of this study is to determine if diagnostic-quality ECG monitoring in patients with coronary artery disease (CAD) during OP-CR is useful in identifying asymptomatic myocardial ischemia, resulting in change(s) in care or medical management. Methods: A retrospective analysis of ECG monitoring was done on all OP-CR patients diagnosed with CAD (n = 1213) from January 2000 through June 2013. Results: Nearly a quarter of the patients (24%; n = 288) displayed at least 1 mm of asymptomatic ST-segment depression at 80 milliseconds after the J-point during at least 1 session of OP-CR. Of these patients, 57% had medical management change(s) compared with 24% for those who did not show ECG changes suggesting ischemia (P < .0001). In patients with asymptomatic ischemia having medical management change(s), 84% resulted directly from OP-CR staff detection. Fewer patients diagnosed with myocardial infarction and coronary artery bypass graft surgery demonstrated ECG signs of ischemia, whereas more patients diagnosed with stable angina and percutaneous coronary interventions demonstrated ECG signs of ischemia. Conclusion: This study demonstrates that most patients with CAD showing asymptomatic ECG signs suggesting ischemia undergo medical management change(s) as a result of the finding. Diagnostic-quality ECG monitoring during OP-CR appears warranted in this population.