Discrimination of Chronic Total Occlusion vs. Subtotal Occlusion by CT Angiography

Study Questions:

What are the anatomical and physiological findings in the coronary computed tomography angiography (CTA) of patients with totally occluded coronary arteries?


The investigators included 486 consecutive patients (median age 63 years, 82% male) who showed a total of 553 completely occluded coronary arteries in coronary CTA. The length of occlusion, side branches, shape of proximal stump, and collateral vessels were measured as anatomical findings. Transluminal attenuation gradient, which reflects intraluminal contrast kinetics and functional extent of collateral flow, was measured as a physiological surrogate. All patients were followed by invasive coronary angiography.


Coronary arteries with CTO showed longer occlusion length (cutoff ≥15 mm), higher distal transluminal attenuation gradient (cutoff ≥ -0.9 Hounsfield units [HU]/10 mm), more frequent side branches, blunted stump, cross-sectional calcification ≥50%, and collateral vessels compared with arteries with subtotal occlusion (STO) (p < 0.001, all). The combination of these findings could distinguish CTO from STO (c-statistics = 0.88; 95% confidence interval [CI], 0.94-0.90; sensitivity 83%, specificity 77%, positive predictive value 55%, negative predictive value 93%; p < 0.001). Percutaneous coronary intervention (PCI) was attempted in 342 arteries and was successful in 279 arteries (82%). The CT findings could predict the unsuccessful PCI (c-statistics = 0.70; 95% CI, 0.65-0.75; sensitivity 63%, specificity 73%, positive predictive value 91%, negative predictive value 31%; p < 0.001).


The authors concluded that noninvasive coronary CTA could discern CTO from SO, and also could predict the success of attempted PCI.


This study reports that comprehensive assessment of anatomical and physiological findings in coronary CTA could discern CTO from SO. Furthermore, CTA findings could also predict the result of PCI. It appears that noninvasive discrimination of CTO from SO before invasive catheterization may be useful for determining a revascularization strategy for patients with totally occluded coronary arteries, but requires additional study.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Interventions and Imaging, Angiography, Computed Tomography, Nuclear Imaging

Keywords: Angiography, Catheterization, Contrast Media, Coronary Angiography, Coronary Occlusion, Diagnostic Imaging, Percutaneous Coronary Intervention, Tomography, X-Ray Computed

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