Coronary Artery Geometry and the Severity of Coronary Atherosclerosis

Study Overview
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Brief Summary
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The purpose of this study is to investigate the potential association of coronary artery geometry, based on coronary CT angiography (CCTA), with the complexity and the severity of coronary atherosclerosis.

Detailed Description
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The angulation of the side branch take-off has been reported to influence the severity of atherosclerosis in coronary bifurcations, as larger angles have been associated with increased plaque burden. Data from computational fluid dynamics studies have confirmed this finding by demonstrating that even in the absence of alterations in the amount of branch flow, a wide angle between the side branches intensifies flow perturbations, increases the spatial endothelial shear stress (ESS) variations in the bifurcation region and the low ESS in the lateral walls, thereby augmenting the atherosclerosis-prone environment. The magnitude of reversed flow, the extension of the recirculation zone and the duration of flow separation during the pulse cycle comprise other haemodynamic parameters which are important in atherogenesis and are amplified by an increased bifurcation angle.

Official Title
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Assessment of Coronary Artery Geometry With Coronary CT Angiography: Evaluation of Atherosclerotic Plaque Burden and Composition

Conditions
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Coronary Artery Disease, Atherosclerosis, Atherosclerotic Plaque, Stable Angina

Intervention / Treatment
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* Diagnostic Test: CCTA


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients referred for cardiac CT angiography Patients without previous history of Coronary Artery Disease (CAD) Age ≥ 18 years Patients giving voluntary written consent to participate in the study Exclusion Criteria: Pregnancy or breast-feeding Patients with serious concurrent disease and life expectancy of < 1 year Patients with a previous history of CAD Patients who refuse to give written consent for participation in the study

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| CCTA Cohort<br>Consecutive patients with suspected coronary artery disease and low/intermediate pre-test probability | Diagnostic Test: CCTA<br>* 128-multislice CT coronary angiography and complex atherosclerotic plaque analysis with the use of CT imaging post-processing techniques.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Left Main Coronary Artery (LMCA) angle of take-off from the aortic root | Measurement using curved Multiplanar Reconstruction (MPR) technique in advantage workstation server | 30 days | 
| Right Coronary Artery (RCA) angle of take-off from the aortic root | Measurement using curved MPR technique in advantage workstation server | 30 days | 
| Left Anterior Descending (LAD) / Left Circumflex (LCx) bifurcation angle | Measurement using curved MPR technique in advantage workstation server | 30 days | 
| Indexed Coronary Volume | Calculated by dividing the total coronary volume to the left ventricle mass, both derived from CCTA (mm3/gr) | 30 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Extent of Coronary Atherosclerosis | Total atherosclerotic plaque volume (mm3) | 30 days | 
| Severity of Coronary Atherosclerosis assessed by using Leiden CTA risk score | Leiden CTA risk score incorporates the presence, extent, severity, location, and composition of coronary artery disease (CAD). Leiden CTA score is calculated using the following approach. First, the presence of CAD is determined in each segment. When plaque is absent the score is 0. When plaque is present a score of 1.1, 1.2 or 1.3 is given according to plaque composition (calcified, noncalcified, and mixed plaque, respectively). Subsequently, this score is multiplied by a weight factor for the location of the segment in the coronary artery tree (0.5 through 6 according to vessel, proximal location and system dominance) and multiplied by a weight factor for stenosis severity (1.4 for ≥50% stenosis and 1.0 for stenosis <50%). The final score (range 0 to 42) is calculated by addition of the individual segment scores. | 30 days | 
| Severity of Coronary Atherosclerosis assessed by using Gensini score | The relative severity of a lesion is indicated using a score of 1 for 1-25% obstruction and doubling that number as the severity of obstruction progresses with each step in the 25-50-75-90-99-100% diameter reduction. Thus, the severity score for each lesion may range from 1 to 32. Furthermore, the score weighed according to the usual blood flow to the left ventricle in each vessel or vessel segment. A multiplying factor is applied to each lesion score based upon its location in the coronary tree, depending on the functional significance of the area supplied by that segment. If a segment is totally occluded or 99% stenosed and receiving collaterals, a collateral adjustment factor is used, and the adjustment is reduced by the extent of disease in the vessel that is the source of collaterals. The final score is the sum of all the lesion scores. | 30 days | 
| Complexity of Coronary Artery Disease [CT-SYNTAX score] | CCTA-derived SYNTAX score (CT-SYNTAX score) is a lesion-based grading tool to characterise the coronary vasculature with respect to the number of lesions and their functional impact, location, and complexity. Higher SYNTAX scores, indicative of more complex disease, are hypothesized to represent a bigger therapeutic challenge and to have potentially worse prognosis. | 30 days | 
| Frequency of occurrence of high-risk plaques | Frequency (%) of occurrence of high-risk plaque features (HU < 30, Remodelling Index > 1.1, napkin-ring sign & spotty calcium) | 30 days | 
| Plaque burden assessment [Modified Duke CAD Index for coronary CTA] | Patients are assigned a risk score between 0-100 based on former patient prognosis data. The score is an extension of the 3-vessel disease score. It also incorporates stenosis severity and calculates with left main stenosis and proximal left anterior descending stenosis. There is a significant difference between patients' cumulative survival for the different categories. Left main plaque with any additional moderate or severe stenosis indicates the worst outcome. | 30 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Geometry, Bifurcation Angle, Cardiac Computed Tomography Angiography, Coronary Artery Disease, Vulnerable Coronary Plaque, Indexed Coronary Volume, Risk Assessment