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Functional CT for Diagnosing CAD
Study Questions:
What is the diagnostic performance of coronary CT angiography (CTA), CT myocardial perfusion (CTP), fractional flow reserve CT (FFRCT), transluminal attenuation gradient (TAG), and their combined use with CTA versus FFR as a reference standard for the detection of hemodynamically significant coronary artery disease (CAD)?
Methods:
The investigators conducted a meta-analysis in adherence with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. PubMed, EMBASE, and Web of Science were searched until September 7, 2017. Bayesian random-effects analysis was used to compute pooled sensitivity, specificity, and summary receiver-operating characteristic curve (SROC) of index tests and compare to FFR as a reference standard. Analyses were performed on vessel and patient levels. Since CTA has an excellent sensitivity, specificity was considered most relevant. Individual FFRCT values were collected.
Results:
Overall, 54 articles and 5,330 patients were included. At vessel level, pooled specificity of CTP (0.86; 95% confidence interval [CI], 0.76-0.93), FFRCT (0.78; 95% CI, 0.72-0.83), and TAG (0.77; 95% CI, 0.61-0.89) were substantially higher than that of CTA (0.61; 95% CI, 0.54-0.68). The addition of FFRCT, CTP, and TAG to CTA resulted in high to excellent specificities (0.80-0.92). SROC at vessel level yielded superior diagnostic accuracy for CTP, FFRCT, and combined CTA and CTP, compared to CTA. A subanalysis of on- versus off-site FFRCT revealed no substantial differences between the sensitivity (0.84 vs. 0.85) and specificity (0.80 vs. 0.73, respectively) of the two techniques. In a second subanalysis, dynamic CTP showed higher sensitivity (0.85 vs. 0.72), but lower specificity (0.81 vs. 0.90, respectively) than static CTP.
Conclusions:
The authors concluded that CTP and FFRCT demonstrated a substantial improvement in the identification of hemodynamically significant CAD compared to CTA.
Perspective:
This study report suggests an additional value of functional CT over anatomic CTA alone for the assessment of hemodynamically significant CAD. Available data suggest that CTP and FFRCT both have the potential to improve identification of patients with hemodynamically significant CAD at reduced health costs, and incorporating them in routine clinical workflow will be helpful. Due to limited evidence, the exact role of TAG is uncertain at this point. Additional clinical studies with use of sophisticated novel imaging protocols and algorithms are indicated to validate the role of functional CT tests in a real-world setting, and to further optimize outcomes among patients with CAD.
Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging
Keywords: Coronary Angiography, Coronary Artery Disease, Diagnostic Imaging, Fractional Flow Reserve, Myocardial, Hemodynamics, Myocardial Ischemia, Myocardial Perfusion Imaging, Secondary Prevention, Tomography, X-Ray Computed
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