A similar accuracy has been reported for correlation of ECG ischemia with anatomic CAD by CCTA.176 Diagnostic accuracy is improved when consid- eration is given to additional non-ECG factors, such as exercise duration, chronotropic incompetence, angina, ven- tricular arrhythmias, heart rate recovery, and hemodynamic response to exercise (ie, drop in systolic BP), or when combination scores such as the Duke treadmill or Lauer scores are applied.118,177 180 Multiple factors in addition to the patient s inability to achieve maximal exercise levels influence the accuracy of the ECG during exercise testing to diagnose obstructive CAD. Resting ECG abnormalities preclude accurate interpretation of exercise-induced changes and reduce test accuracy; these include abnormalities affecting the ST segment, such as LV hypertrophy, LBBB, ventricular-paced rhythm, or any resting ST-segment depression $0.5 mm. Although some have proposed calculating the difference from rest to exercise of changes $1 mm for patients with significant resting ST- segment changes, the accuracy of this approach has been less extensively studied and validated. The interpretation of ST- segment changes in patients with right bundle-branch block can be limited, especially in the precordial leads. Certain medications, including digitalis, also influence ST-segment changes and can produce ischemic ECG changes that are frequently false positive findings. In addition, anti-ischemic therapies can reduce heart rate and myocardial workload, and therefore, a lack of ischemic ECG changes can reflect false negative findings when the test is used to diagnose SIHD. It is routine practice to withhold beta-blocker therapy for 24 to 48 hours before testing. Patients who are candidates for an exercise ECG must be able to exercise and must have an interpretable ECG, which is defined as a normal 12-lead ECG or one with minimal resting ST-T-wave abnormalities (,0.5 mm). 2.2.3.2. 