In general, the diagnostic accuracy of stress testing is similar in patients with and without known SIHD (Section 2.2.3). A few meta-analyses examining the effect of prior MI on diagnostic accuracy have found that the specificity of exercise ECG was higher in mixed popula- tions,145 whereas the diagnostic performance of exercise echocardiography was reduced. In contrast, the specificity of exercise SPECT was increased because of the predictive value of total stress perfusion abnormalities, which in- cludes both the risk of ischemia plus infarcted myocardi- um.91 Although CMR LGE imaging detects MI, current evidence indicates that assessment of myocardial ischemia provides incremental diagnostic1249 and prognostic value above LGE detection of infarction284 in patients with or without known SIHD. In contrast to stress testing, the diagnostic value of CCTA differs in patients with and without known CAD. Limitations of image quality relating to coronary calcifi- cation, coronary stents, or vascular clips can reduce diagnostic accuracy, and revascularization also affects results. The large caliber of venous conduits facilitates the assessment of patients who have undergone CABG with CCTA and has sensitivities of 89% to 98% and specifici- ties of 89% to 97% for the identification of .50% diameter stenoses in grafts on invasive coronary angiog- raphy.1244 1246 The accurate evaluation of coronary stents with CCTA depends on the material and diameter of the stent, with image artifacts related to the stents metallic structure preventing assessment of 9% to 11% of stents.1247,1248 Typically, stents .3 mm in diameter can be assessed,1248 with sensitivities for detecting a .50% di- ameter in-stent restenosis on invasive coronary angiogra- phy of 86% to 94% and specificities of 91% to 93%. 6.3.2. Noninvasive Testing in Known SIHD Asymptomatic (or Stable Symptoms): Recommendations See Table 21 for a summary of recommendations from this section. Table 21. 