Prospective Identification of High-risk Coronary Plaques Through Non-invasive Imaging

Study Overview
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Brief Summary
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Cardiovascular disease remains the leading cause of death worldwide. Identifying individual patients at risk of a suture adverse events, including myocardial infractions (heart attacks), remains a major diagnostic challenge. Recent studies have shown that coronary plaques responsible for hear attack are composed of a large lipid core with a thin overlying fibrous cap. Although these features can be identified using invasive imaging modalities, non-invasive imaging options remain limited due to their poor spatial resolution. Recently the investigators have developed and validated a novel tool that will allow us to characterise coronary plaque composition based on dual source CT images. Our aim is to assess this tool within a cohort of patients who have already undergone a coronary CT as part of a previous study.

Detailed Description
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Reliable identification of coronary plaque at risk of causing future adverse cardiovascular events would allow patient-specific targeting of intensive therapy. The majority of events are precipitated by coronary plaque rupture, with ruptured plaques exhibiting a large necrotic, lipid core with superimposed thrombus. The proposed precursor lesion shares similar plaque compositional features to ruptured plaques but with a thin overlying fibrous cap and is termed a thin-cap fibroatheroma (TCFA)1. At present there is a major emphasis on imaging modalities that can identify these higher-risk plaque subtypes. We have previously validated an invasive imaging modality, virtual-histology intravascular ultrasound (VH-IVUS) against histology, and found that VH-IVUS identified TCFA with a diagnostic accuracy of 74%2. In prospective studies, VH-defined TCFAs were associated with a 7x greater risk of future events than other plaque subtypes3. Although this technique shows promise in permitting plaque-based risk stratification, it is limited by its invasive nature. Thus, alternate, non-invasive imaging options are required for more widespread risk assessment. Recently, we have devised a novel method of creating Plaque Maps using CT attenuation data individualised to each patient (Figure 1), which permits identification of coronary plaque components with a diagnostic accuracy of 75%-85%4. However, whilst CT Plaque Maps could identify fibroatheroma with similar diagnostic accuracy to VH-IVUS (79% vs. 74%), the spatial resolution of CT was unable to detect the thin fibrous cap and distinguish fibroatheroma from TCFA (Figure 2). More recently we have introduced necrotic core/fibrous plaque ratio as a possible Plaque Map surrogate for identification of TCFA. Using a ratio of >0.58, the sensitivity to detect a TCFA was 84% and specificity 75%; an improvement over all previously identified CT-defined features of high risk plaques4. Whether this novel strategy can prospectively improve identification of plaque vulnerability is unproven.

Official Title
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Prospective Identification of High-risk Coronary Plaques Through Non-invasive Imaging

Conditions
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Coronary Plaques

Intervention / Treatment
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* Other: Telephone interview


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age >18 years The ability to provide informed consent. Previously part of CTA accuracy validation study Exclusion Criteria: • The inability of the participant to provide informed consent

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 |
| --- | --- |
| cohort of patients with suspected coronary artery disease<br>a cohort of patients with suspected coronary artery disease going forward for conventional angiography and (2) whether CT-TCFA is associated with future adverse cardiovascular events. | Other: Telephone interview<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| CT-defined TCFA association with future adverse cardiovascular events |  | 7 years post surgery |