CT features in the early and late stages of chronic total coronary occlusions

Objectives: To investigate the morphologic characteristics of early and late stages of chronic total coronary artery occlusions (CTO) in coronary computed tomography angiography (coronary CTA).

Methods: We retrospectively analyzed patients who underwent coronary CTA and invasive coronary angiography and had at least one CTO with known duration. The following parameters were obtained in coronary CTA: calcification of the occluded segment; stump morphology; lesion length; remodeling index; presence of intra-occlusion linear contrast enhancement; and density of non-calcified CTO components. CT parameters were compared between patients with early (duration ≤ 12 months) and late (duration > 12 months) stage CTO.

Results: One-hundred and twelve patients with 124 chronically occluded coronary arteries were analyzed. Fifty nine patients had early stage CTOs (62 lesions) and 53 patients had late stage CTOs (62 lesions). Calcification was more severe in late-stage versus early CTOs (Agatston score: early stage, 27.4 ± 46.7 vs. late stage, 58.3 ± 112.4; p = 0.049). Remodeling index was lower in late-stage CTOs (early stage, 0.96 ± 0.2 vs. late stage, 0.88 ± 0.22; p = 0.034). In patients with late stage CTO, the presence of intra-occlusion linear enhancement was more likely (45.2% vs 14.5%, p < 0.001), and the density of non-calcified components was significantly higher (85.4 ± 27.2 HU vs. 65.7 ± 30.1 HU, p < 0.001). Stump morphology was not different between the two groups.

Conclusions: Coronary CTA reveals differences between chronic total coronary occlusions of longer and shorter duration. A long duration is associated with focal calcification and negative remodeling, as well as intra-occlusion enhancement and a higher density of non-calcified components.