| Part One The morphological assessment of coronary total occlusions by computed tomography angiography for prediction of outcome of percutaneous coronary interventionPurpose: The aim of the study was to evaluate the morphological parameters in coronary total occlusion lesions(C TO) observed by coronary computed tomography angiography(CCTA) and its correlation with outcome of percutaneous coronary intervention(PCI).Methods : All patients gave written informed consent, and the study protocol was approved by the hospital ethics committee. Consecutive patients with CTO confirmed by an initial invasive coronary angiography(ICA) were prospectively enrolled to have a CCTA prior to their staged PCI. Linear intra-thrombus enhancement was defined as the linear- like enhanced opacity traversing the non-opacified occluded segment, with attenuation higher than 120 Hounsfield units. Angiographic features including lesion length, linear intra-thrombus enhancement length and calcific ation score were measured by CCTA. Univariate and multivariate statistical tests were performed to identify variables associated with successful PCI.Results: Eighty patients with 88 C TO lesions were included in this study. There were 51 lesions successfully recanalized by PCI. Lesion length was longer in PCI failure group(p=0.043). Linear intra-thrombus enhancement was observed in 59% of the 30 successfully performed PCI cases(30/51). However, for the group of patients with failed PCI, linear enhancement was not found in 19% of those patients(7/37, p<0.001 as compared to successful cases). Tortuous course revealed to be the only angiographic parameter associated with unfavorable PCI outcome(p=0.008). The presence of linear intra-thrombus enhancement pro ved by multivariate analysis to be the only independent predictor of PCI success(odds ratio=4.926, 95%CI 1.646-14.74, p=0.004).Conclusions: The presence of CCTA visible linear intra-thrombus enhancement within the occluded segment predicts better outcome of PCI of C TOs.Part Two The clinical significance of "Reverse attenuation gradient sign" observed at computed tomography for differentiation of coronary chronic total occlusion and subtotal occlusionPurpose: To study the clinical significance of “reverse attenuation gradient(RAG) sign” in patients with occlusive coronary artery disease observed by coronary computed tomography angiography(CCTA).Materials and methods: All patients gave written informed consent and the institutional review board committee approved the study protocol. Eighty consecutive patients(mean age: 67±12 years, range 35 to 87 years, 62 males [mean age: 65.8±12.5, range 35 to 86 years] and 18 females [mean age: 71.7±9.3, range 58 to 87 years]) with 94 occlusive lesions were prospectively enrolled in this study. Invasive coronary angiography confirmed 49 chronic total occlusions(C TOs) and 45 subtotal occlusions(SOs). “RAG sign” was d efined as the reverse intraluminal opacification gradient of vessels distal to the occlusive lesions, which has the lower attenuation in proximal segment and gradually increased attenuation along the vessel. Other parameters, like lesion length and CCTA visible bridging collaterals, were also recorded. Mann-Whitney-Wilcoxon test and Fisher’s exact test were used for comparison.Results:The CTO group revealed significantly more frequent the presence of RAG sign than did the SO group(65.3% versus 6.7%, p<0.001). Similarly, significant difference of measurements of the attenuation gradient(5.1±13.4HU/mm versus-13.4±8.7HU/mm, p<0.001) and lesion length(23.6±22.7mm versus 6±3mm, p<0.001) were also noted between both groups. Bridging collaterals were only p resent in 4 cases of CTO at CCTA. All segments with RAG on CCTA were shown by invasive coronary angiography to be supplied by retrograde collaterals. When combination of all those parameters was employed for diagnosis of CTO, the sensitivity and specificity were 90 % and 93 % respectively.Conclusion: The "RAG sign" represents the retrograde collateral flow distal to an occlusive lesion. This sign is highly specific for chronic total occlusion and helps to differentiate C TOs from SOs.Part Three Collateral vessel opacification by computed tomography in patients with coronary total occlusion and its relation with downstream myocardial infarctionPurpose: To assess the correlation between the filling pattern of distal coronary vessels in patients with chronic total occlusion(CTO) observed at coronary computed tomography angiography(CCTA) and the extent of downstream myocardial infarction(MI).Materials and methods: All patients gave written informed consent and the institutional review board committee approved the study protocol. 97 patients(mean age: 68.5±11.5, range 38 to 87 years, 77 males and 20 females) with 106 CTOs were prospectively enrolled. Distal filling of epicardial segment was semi-quantitatively classified using a 4-point scale according to patterns at CCTA(score 0=absence of distal filling, score 1= partial distal filling with length less than 1/3, score 2=partial distal filling with length betwee n 1/3 to 2/3, score 3=complete or partial distal filling with length longer than 2/3). CCTA score 3 was considered as well-developed collaterals. Downstream myocardial infarction transmurality and wall motion abnormality was verified by cardiac MR semi-quantitatively. Mann-Whitney U-test and t-test were used for comparison.Results: CCTA revealed 3 lesions of score 0, 21 lesions of score 1, 35 lesions of score 2 and 47 lesions of score 3. Non-MI subgroup was associated with higher collateral grading by CT angiography whereas transmural-MI subgroup was associated with lower collateral grading(p=0.005). Compared to poorly-developed(score 0-2) collaterals group, well-developed(score 3) collaterals group correlated to lower summed transmurality score(p<0.001) and lower summed regional wall motion abnormality score(p=0.029).Conclusion: The presence of well-developed distal collaterals as revealed by CCTA in patients with CTO lesions correlates to the lower frequency and extent of downstream MI.Part Four Evaluation of collateral channel classification by computed tomography: the feasibility study with reference to invasive coronary angiographyPurpose: To study the feasibility of evaluation of collateral channel(CC) classification in patients with coronary chronic total occlusion(C TO) by coronary computed tomography angiography(CCTA) with reference to invasive coronary angiography(ICA) validation.Materials and methods: We retrospectively included CTO-confirmed patients who underwent both CCTA and ICA within one month. Collaterals were classified by CCTA into three types: CC0, no continuous connection between donor and recipient vessel; CC1, continuous thread- like connection; CC2, continuous, small sidebranch- like connection. With comparison to ICA results, the diagnostic performance of CCTA-based CC classification was further assessed.Results: 118 patients with 132 ICA-confirmed C TO lesions were inc luded. Compared to ICA-based evaluation, good overall diagnostic accuracy of CT-based CC classification was observed(78%, 103/132, kappa=0.674, p<0.001). CCTA was also revealed to be accurate in terms of assessment of collateral tortuosity(76.2%, 77/101) and identification of principal donor vessel(70.3%, 71/101). Impaired diagnostic performance was observed in sub- group of septal collaterals as the accuracy for evaluation of the above parameters was 60.6%(20/33), 72.7%(24/33) and 45.5%(15/33) respectively.Conclusion: Non- invasive evaluation of CC classification by CCTA correlates well with IC A findings. In addition, the septal collaterals are much less visible at CCTA than epicardial collaterals. |
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