When ischemia is non-transmural (also referred to as sub-endocardial), non-ischemic myocardium will overlie the ischemic region. Therefore, the injury current will flow towards any and all electrodes placed over the epicardial surface during the TQ segment, resulting in TQ elevation; and away from these electrodes during the ST segment, causing ST depession, regardless of whether or not the electrodes overlie the ischemic region. As a result, ST depression will be recorded on the body surface electrocardiogram and the leads in which the ST segment depression occurs will not identify the ischemic region.