Natural History of Untreated Coronary Total Occlusions Revealed with Follow-Up Semi-Automated Quantitative Coronary CT Angiography: The Morphological Characteristics of Initial CT Predict Occlusion Shortening

Radiomics Analysis of Pericoronary Adipose Tissue From Baseline Coronary Computed Tomography Angiography Enables Prediction of Coronary Plaque Progression

PURPOSE

The relationship between plaque progression and pericoronary adipose tissue (PCAT) radiomics has not been comprehensively evaluated. We aim to predict plaque progression with PCAT radiomics features and evaluate their incremental value over quantitative plaque characteristics.

PATIENTS AND METHODS

Between January 2009 and December 2020, 500 patients with suspected or known coronary artery disease who underwent serial coronary computed tomography angiography (CCTA) ≥2 years apart were retrospectively analyzed and randomly stratified into a training and testing data set with a ratio of 7:3. Plaque progression was defined with annual change in plaque burden exceeding the median value in the entire cohort. Quantitative plaque characteristics and PCAT radiomics features were extracted from baseline CCTA. Then we built 3 models including quantitative plaque characteristics (model 1), PCAT radiomics features (model 2), and the combined model (model 3) to compare the prediction performance evaluated by area under the curve.

RESULTS

The quantitative plaque characteristics of the training set showed the values of noncalcified plaque volume (NCPV), fibrous plaque volume, lesion length, and PCAT attenuation were larger in the plaque progression group than in the nonprogression group ( P < 0.05 for all). In multivariable logistic analysis, NCPV and PCAT attenuation were independent predictors of coronary plaque progression. PCAT radiomics exhibited significantly superior prediction over quantitative plaque characteristics both in the training (area under the curve: 0.814 vs 0.615, P < 0.001) and testing (0.736 vs 0.594, P = 0.007) data sets.

CONCLUSIONS

NCPV and PCAT attenuation were independent predictors of coronary plaque progression. PCAT radiomics derived from baseline CCTA achieved significantly better prediction than quantitative plaque characteristics.

Coronary chronic total occlusion on coronary CT angiography: what radiologists should know?

Coronary chronic total occlusion (CTO) often occurs in patients with obstructive coronary artery disease, which remains one of the greatest challenges for interventional cardiologists. Coronary computed tomography angiography (CCTA) with its emerging post-processing techniques can provide a detailed assessment of CTO lesions before percutaneous coronary intervention (PCI), playing an important role in the clinical management of CTO PCI, from early diagnosis, pre-procedural outcome prediction, the crossing algorithm planning, intraprocedural guidance, and finally post-procedural assessment and follow-up. In addition, the feasibility of CT perfusion (CTP) in patients with CTO has been validated. Combined CCTA and CTP have the great potential to be the one-stop-shop imaging modality for assessing both anatomy and function of CTO lesions. This review aims to make radiologists understand the role of CCTA in the diagnosis and assessment of CTO lesions, thus assisting interventionalists in optimizing CTO PCI crossing strategies with the expertise of radiologists.Critical relevance statement The anatomical features of CTO on CCTA can reveal the complexity of CTO lesions and are associated with CTO PCI outcome, thus helping interventionalists optimize CTO PCI crossing strategies.Key points • CTO is the common lesion in invasive coronary angiography, and CTO PCI is technically difficult and its success rate is relatively low.• Length, collaterals, and attenuation-related signs can help distinguish CTO from subtotal occlusion.• The anatomical features of CTO lesions can help grade the difficulty of CTO PCI and predict procedural outcomes and long-term outcomes of CTO PCI.• The real-time fusion of CCTA with fluoroscopic angiography can be applied in highly complicated CTO lesions.• After CTO PCI, CCTA can help guide a second CTO PCI re-entry or follow up stent patency.

Association between myocardial ischemia and plaque characteristics in chronic total occlusion

BACKGROUND

Myocardial ischemia varies in chronic total occlusion (CTO) despite the occluded artery. We analyzed whether it is associated with the plaque characteristics of the occluded segment.

METHODS

We retrospectively enrolled 100 patients with CTO who underwent myocardial perfusion single-photon emission computed tomography (SPECT) and coronary computed tomography angiography (CCTA) within 2 months. CTO-related ischemia was classified as moderate to severe (summed difference score [SDS] of the CTO territory ≥ 5) or mild or none (SDS < 5) on SPECT. Using CCTA, the atherosclerotic plaques of the occluded segment were subdivided into low-density (- 100-30 HU), intermediate-density (31-350 HU), and high-density (351-1000 HU) plaques. The plaque composition was compared according to the severity of CTO-related ischemia.

RESULTS

Moderate-to-severe CTO-related ischemia (n = 23) showed significantly higher proportion of intermediate-density plaques (72.4% vs. 64.0%), intermediate/low-density (7.10 vs. 3.65) and intermediate-to-high/low-density (7.78 vs. 3.80) plaque ratios, frequent shorter occlusion (30% vs. 6%), and lower volume (26.5 mm3 vs. 58.8 mm3) and proportion (11.4% vs. 20.8%) of low-density plaques. Multivariable analysis revealed significant associations between higher proportion of intermediate-density plaques and moderate-to-severe CTO-related ischemia, independent of occlusion length.

CONCLUSION

Higher proportion of intermediate-density plaques in the occluded segment was associated with the moderate-to-severe CTO-related ischemia.

Endovascular revascularization of multi segment chronically occluded ICA

This case report describes a novel endovascular method for treating chronically occluded internal carotid artery (COICA). The patient is a 55-year-old male with vascular risk factors who presented to an outside institution with right-sided weakness and dysarthria, was diagnosed as having a stroke, and discharged with medical management. The patient's symptoms failed to improve throughout the week prompting him to visit another outside institution, where computed tomography (CT) angiography showed bilateral occlusion of the ICAs at their origins extending intracranially. The patient was then transferred to our hospital, where head CT revealed bilateral acute infarcts predominantly in the left centrum ovale/corona radiata and left temporoparietal region. CT perfusion showed a large area of hypoperfusion in the entire left hemisphere as well as part of the right hemisphere (mismatch volume of 438-526 mL). The patient had significant neurological deficits despite sustained high perfusion pressure, so the following morning, the patient was taken for angiography showing complete occlusion of the left ICA with support mostly from the left external carotid artery (ECA)/ophthalmic collateralization. The microcatheter was able to be advanced to the level of the ophthalmic segment of the left ICA, so the decision was made to proceed with stenting from the left ophthalmic ICA to the cervical ICA. Seven consecutive coronary-carotid stents were placed to essentially reconstruct the left ICA. Post-stenting, the patient was treated with an Integrilin drip and transitioned to Aspirin and Brilinta the following morning. The patient's symptoms markedly improved after the procedure. CT perfusion, as well as diffusion magnetic resonance imaging (MRI), revealed recovery of the patient's penumbra and stability of the existing infarcts despite the delayed nature of revascularization respectively. This is a rarely reported study in literature describing the successful deployment of multiple stents in recreating the ICA from its extracranial to intracranial portion.

Inclusion of quantitative high-density plaque in coronary computed tomographic score system to predict the time of guidewire crossing chronic total occlusion

OBJECTIVE

This study aimed to establish a new scoring system that includes histological quantitative features derived from coronary computed tomographic angiography (CCTA) to predict the efficiency of chronic total occlusion percutaneous coronary intervention (CTO-PCI).

METHODS

This study analyzed clinical, morphological, and histological characteristics of 207 CTO lesions in 201 patients (mean age 60.0 [52.0-65.0] years, 85% male), which were recruited from two centers. The primary endpoint was a guidewire successfully crossing the lesions within 30 m. The new predictive model was generated by factors that were determined by multivariate analysis. The CCTA plaque (CTAP) score that included a quantitative plaque characteristic was developed by assigning an appropriate integer score to each independent predictor, then summing all points. In addition, the CTAP score was compared with other predictive scores based on CCTA.

RESULTS

The endpoint was achieved in 63% of the lesions. The independent predictors included previous CTO-PCI failure, the proximal blunt stump, proximal side branch, distal side branch, occluded segment bending > 45°, and high-density plaque volume (fibrous volume + calcified volume) ≥ 19.9 mm³. As the score increased from 0 to 5, the success rate of the guidewire crossing within 30 m decreased from 96 to 0%. Comparing the CTAP score with other predictive scores, the CTAP score showed the highest discriminant power (c-statistic = 0.81 versus 0.73-0.77, p value 0.02-0.07). The CTAP score showed similar results for procedural success.

CONCLUSION

The CTAP score efficiently predicted the guidewire crossing efficiency and procedural success.

KEY POINTS

• An increase in high-density plaque volume (fibrous + dense calcium) was more probable to reduce the efficiency of crossing and lead to procedural failure. • The new prediction scoring system with the addition of the quantitative characteristics of plaques had an improved predictive ability compared with the traditional prediction scoring system.

Efficacy of Coronary Computed Tomography Angiography for the De Novo Detection of Chronic Total Occlusion Prior to Coronary Angiography: A Preliminary and Retrospective Study

Coronary computed tomography angiography (CCTA) offers high-resolution anatomic characterization of the coronary vasculature but may be suboptimal for lesions dependent on real-time visualization of flow including chronic total occlusion (CTO). In CTOs, heavy calcification and distal vessel opacification from collateralization may confound luminal assessment. Several studies have examined the role of CCTA in characterizing known CTOs to guide percutaneous coronary intervention (PCI). However, the efficacy of CCTA in the de novo diagnosis of CTOs prior to coronary angiography (CAG) has not been demonstrated. A total of 233 consecutive patients who presented for CAG within a 3-month period of having CCTA were retrospectively reviewed. Those patients with prior diagnosis of CTO or prior bypass of the occluded vessels were excluded. Sensitivity and specificity analysis of CCTA in identifying CTOs using CAG as the gold standard was performed. The prevalence of CTO was 21.11% in the population that met criteria for analysis (n = 199). The sensitivity of CCTA in predicting CTO was 57.1%, while the specificity was 96.8%. The positive predictive value and negative predictive value of CCTA in detection of CTO were 82.8 and 89.4%, respectively. Our study shows that CCTA has excellent specificity but poor sensitivity in the detection of CTO thus limiting its clinical use in de novo diagnosis. Further studies to determine the effect of de novo CTO diagnosis on clinically important procedural factors, such as radiation exposure, contrast use, and need for repeat procedures, are warranted and may implicate a role for CCTA in this setting.

Use of Coronary Computed Tomographic Angiography to Facilitate Percutaneous Coronary Intervention of Chronic Total Occlusions

Chronic total coronary occlusions (CTO) are found frequently in coronary artery disease; however, the technical challenge to open the occlusion by percutaneous coronary intervention is considerably higher than for nonocclusive lesions. The angiographic analysis is limited by the inability to visualize the occluded segment and requires a dual injection approach from donor and recipient vessel to assess the CTO. Therefore, imaging of the CTO by computed tomographic angiography can provide additional information on the vessel course within the CTO segment, specifically the degree and extent of calcification, and maybe even be superior to angiography to analyze the proximal cap morphology. This had been integrated in a score to predict the interventional success. This information provides a valuable means to better plan the procedure and the required strategy. In addition, an integration of the computed tomographic angiography is possible by synchronization with the gantry position and movement of the angiography system during percutaneous coronary intervention, illustrating the course of the occluded segment and possible obstacles in the way. It remains to be established which patient will most likely profit from this additional preprocedural examination involving increased radiation and contrast media exposure and institutional expenses.