If ST-T-wave changes or Q waves had been present, the likelihood of CAD would be higher in each entry of the table. CAD indicates coronary artery disease; and ECG, electrocardiogram. Reprinted from Pryor et al.71 Fihn et al Stable Ischemic Heart Disease: Full Text e371 rely on the principles embodied within the ischemic cascade (Figure 7), in which graded ischemia of increasing severity and duration produces sequential changes in perfusion, relax- ation and contraction, wall motion, repolarization, and, ulti- mately, symptoms, all of which can be detected by an array of cardiovascular testing modalities.75 The production of ische- mia, however, depends on the severity of stress imposed (ie, submaximal exercise can fail to produce ischemia) and the severity of the flow disturbance. Coronary stenoses ,70% are often undetected by functional testing. Because abnormalities of regional or global ventricular function occur later in the ischemic cascade, they are more likely to indicate severe stenosis and, thus, demonstrate a higher diagnostic specificity for SIHD than do perfusion defects, such as those seen on nuclear MPI. Isolated perfusion defects, on the other hand, can result from stenoses of borderline significance, raising the sensitivity of nuclear MPI for underlying CAD but lowering the specificity for more severe stenosis. The recent availability of multislice CCTA allows for the noninvasive visualization of anatomic CAD with high- resolution images similar to invasive coronary angiography. 