Validation of Coronary Calcium Subtraction to Improve Diagnostic Accuracy of Coronary CT Angiography

Study Overview
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Brief Summary
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Coronary calcium hampers accurate evaluation of the coronary arteries with coronary computed tomography angiography (CCTA). A novel approach to potentially overcome this limitation is coronary calcium subtraction. The primary hypothesis of the study is: - Coronary calcium subtraction CCTA will improve diagnostic accuracy as compared to conventional CCTA on a per-patient basis

Detailed Description
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CCTA is a very important clinical method for the clinical evaluation of patients with chest pain of potential cardiac ischemic origin. However Coronary calcification and/or previously implanted coronary stents may limit the diagnostic accuracy of CCTA. A novel approach - coronary calcium subtraction - has been developed to potentially overcome this limitation. Study Objective: To assess diagnostic accuracy using coronary calcium subtraction coronary CT angiography (CCTA) as compared to conventional CCTA. Material and Methods: A total of 200 patients with suspected or known coronary artery disease (CAD) who have been referred for invasive coronary angiography (ICA) will prior to ICA undergo additional research CCTA with the newly developed coronary calcium subtraction protocol. Based on the coronary calcium scan (CS), coronary calcium score will be calculated according to the Agatston score. Conventional contrast enhanced CCTA studies will be analyzed for image quality and the presence and extent of coronary stenosis. Using a dedicated algorithm, subtraction will be performed on all datasets to obtain CCTA subtraction images. Subtracted images will be analyzed similar to the conventional CCTA images. ICA will serve as the gold standard. Image quality will be compared between conventional and subtracted CCTA. In addition, diagnostic accuracy in the evaluation of coronary stenosis as determined on ICA will be compared. Finally, factors influencing the performance of coronary calcium subtraction will be evaluated.

Official Title
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Prospective International Study of Coronary Substraction Using 320 Row-detector CT

Conditions
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Coronary Artery Disease

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 55 Years Scheduled for invasive coronary angiography Logistically possible to perform CCTA before invasive evaluation Exclusion Criteria: Known Iodine-contrast allergy Estimated GFR below 50 ml/min Atrial fibrillation or other persistence cardiac arrythmia Contraindication to betablockers (bronchospasm, LVEF less than 40%) Implanted PM or ICD Previous mechanical heart valve surgery Inability to maintain breath-hold for at least 5 sec Patient-related condition resulting the inability of the patient to understand the informed consent form of the study

Ages Eligible for Study
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Minimum Age: 55 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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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diagnostic accuracy of Coronary Subtraction Coronary CT angiography | Sensitivity, Specificity, Negative and Positive predictive value of Coronary Subtraction CT angiography by visual assessment to identify a >50% coronary stenosis as defined by invasive coronary angiography on a patient by patient level. | Within 90 days of ICA and CCTA | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Coronary CT angiography reader confidence | Coronary CT angiography reader confidence by a 3 level visual scale assessed on CT images without and with Coronary Calcium Subtraction | Within 90 days of ICA and CCTA | 
| Coronary stenosis severity in non-diagnostic or partially diagnostic segments by conventional CCTA | In coronary segments deemed non-diagnostic or partially diagnostic due to calcification or coronary stents by conventional CCTA concordance of stenosis severity by Coronary Subtraction CT angiography and invasive quantitative coronary angiography is assessed | Within 90 days of ICA and CCTA | 
| Coronary revascularization | On a patient by patient level the ability of CCTA to predict need for coronary revascularization (PCI or CABG) is assessed using CCTA without and with coronary calcium subtraction | Within 30 days after CCTA | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Multidetector Computed Tomography, Coronary Stenosis, Coronary Artery Disease, Angina Pectoris