OBJECTIVES: The aim of this study was to investigate whether noninvasive discrimination of chronic total occlusion (CTO), a complete interruption of coronary artery flow, and subtotal occlusion (STO), a functional total occlusion, is feasible using coronary computed tomography angiography (CTA). CTO and STO may be different in pathophysiology and clinical treatment strategy.
METHODS:Â We 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.
RESULTS:Â Coronary arteries with CTO showed longer occlusion length (cutoff â‰¥15 mm), higher distal transluminal attenuation gradient (cutoff â‰¥âˆ’0.9 Hounsfield units [HU]/10 mm), more frequent side branches, blunted stump, cross-sectional calcification â‰¥50%, and collateral vessels compared with arteries with STO (p < 0.001, all). The combination of these findings could distinguish CTO from STO (c-statistics = 0.88 [95% confidence interval: 0.94 to 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 computed tomography findings could predict the unsuccessful PCI (c-statistics = 0.70 [95% confidence interval: 0.65 to 0.75], sensitivity 63%, specificity 73%, positive predictive value 91%, negative predictive value 31%; p < 0.001).
CONCLUSIONS:Â Noninvasive coronary CTA could discern CTO from STO, and also could predict the success of attempted PCI.
WHAT IS KNOWN? Discrimination of CTO from STO before cardiac catheterization is of clinical value because PCI is attempted less frequently for CTO, with a higher rate of unsuccessful procedures and late restenosis compared with non-CTO. However, noninvasive discrimination of CTO from STO remains a challenge.
WHAT IS NEW? This study showed that comprehensive assessment of anatomical and physiological findings in coronary CTA on the basis of the presumed pathogenesis of CTO, a progression of organized thrombus and collagen tissues filling up to the ostium of side branches accompanied by collateral vessels supplying subtended myocardium, could discern CTO from STO and could also predict the result of PCI.
WHAT IS NEXT? Noninvasive discrimination of CTO from STO before invasive catheterization may be useful for determining a revascularization strategy for patients with totally occluded coronary arteries.