Special Patient Group: Risk Assessment in Patients Who Have an Uninterpretable ECG Because of LBBB or Ventricular Pacing Isolated false-positive reversible perfusion defects of the septum on nuclear MPI due to abnormal septal motion causing a reduction in diastolic filling time have been reported in patients with LBBB without significant coronary stenosis. Compared to patients without LBBB, use of exercise stress in patients with LBBB or ventricular pacing substan- tially reduced diagnostic specificity.289,292 Although a normal nuclear perfusion scan in this clinical setting is highly accurate in indicating the absence of a significant coronary stenosis and a low risk of subsequent cardiac events,288 an abnormal study can be nondiagnostic.148,287 In patients with LBBB on a rest ECG, dobutamine stress echocardiography is less sensitive but more specific than nuclear MPI in detecting coronary stenosis and provides prognostic information that is incremental to clinical findings.344 One meta-analysis dem- onstrated that abnormal stress nuclear MPI and stress echo- cardiography each confer an up to 7-fold increased risk of adverse cardiovascular events.148 3.2.3. Prognostic Accuracy of Anatomic Testing to Assess Risk in Patients With Known CAD 3.2.3.1. Coronary CT Angiography Given the high accuracy in detecting angiographically signif- icant coronary stenosis, estimates of cardiovascular risk according to the Duke CAD index with data obtained via CCTA appear to be as accurate as those obtained from cardiac catheterization. 