Troponin to Risk Stratify Patients for Computed Tomography Coronary Angiography

Study Overview
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Brief Summary
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Most patients presenting to hospital with chest pain are discharged home without further tests once a heart attack has been ruled out. Current strategies to assess patients with a suspected heart attack involve blood tests to measure troponin, a protein released into the bloodstream when the heart muscle is damaged. Despite having had a heart attack ruled-out, some patients have unrecognised coronary heart disease and are at risk of having a heart attack in the future. However, we do not know what is the best approach to identify and treat these patients. This study will use a heart scan known as computed tomography coronary angiogram (CTCA) to look for underlying coronary heart disease in patients who have had a heart attack ruled out. In an earlier study, we performed this scan in patients referred to the outpatient cardiology clinic with stable chest pain and found that this improved the diagnosis of coronary heart disease, leading to improvement in patient care that prevented many future heart attacks. Our research has also demonstrated that troponin levels below the threshold used to diagnose a heart attack identify those who are at greater risk of having a heart attack in the future. The aim of this study is to confirm whether these low levels of troponin can identify patients who have underlying coronary heart disease and may benefit from further testing and preventative treatment.

Detailed Description
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Using a newer, more sensitive troponin test, we now know that troponin levels even below the threshold used to diagnose a heart attack identify patients who are at risk of having a heart attack in the future. Our research in patients with stable chest pain demonstrated that computed tomography coronary angiogram (CTCA) improved the diagnosis of coronary heart disease, leading to improvement in patient care that prevented many future heart attacks. This study will build on these two major strands of research to confirm whether these low levels of troponin can identify patients who have underlying coronary heart disease and may benefit from further testing and preventative treatment. The investigators will evaluate consecutive patients presenting to hospital with suspected acute coronary syndrome and cardiac troponin concentration within the normal reference range for the presence of underlying coronary artery disease. All participants will be invited for an outpatient CTCA. Findings from this study will help inform a randomised controlled trial to evaluate the role of CTCA in patients who have a heart attack ruled out, but are identified as intermediate risk on troponin testing.

Official Title
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Troponin Within the Normal Reference Range to Risk Stratify Patients With Acute Chest Pain for Computed Tomography Coronary Angiography

Conditions
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Coronary Artery Disease, Acute Coronary Syndrome

Intervention / Treatment
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* Diagnostic Test: Computed Tomography Coronary Angiography


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Presentation to hospital with acute chest pain or equivalent symptoms of suspected acute coronary syndrome Maximum high-sensitivity cardiac troponin I concentration below the 99th centile (16 ng/L for women and 34 ng/L in men) Exclusion Criteria: Diagnosis of myocardial infarction during index presentation Clear alternative diagnosis for index presentation Recent CT or invasive coronary angiogram (within 1 year) Patient inability to undergo CT scanning, due to severe renal failure (estimated glomerular filtration rate <30 mL/min) or major allergy to iodinated contrast media Pregnancy or breast feeding Inability to give informed consent Further investigation for coronary artery disease would not in the patient's interest, due to limited life expectancy, quality of life or functional status

Ages Eligible for Study
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Minimum Age: 30 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 |
| --- | --- |
| Patients without myocardial injury<br>Patients without myocardial injury will be recruited in a 2:1 fashion stratified by peak high-sensitivity cardiac troponin I concentration above and below a threshold of 5 ng/L. | Diagnostic Test: Computed Tomography Coronary Angiography<br>* In order to optimise the quality of the Computed Tomography Coronary Angiography scan images, participants might be given tablets or an injection (e.g. beta-blockers, calcium channel antagonist, ivabradine) to slow their heart rate and glyceryl trinitrate (GTN) following local protocol guidance.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of participants with obstructive coronary artery disease | Proportion of participants with >50% stenosis in the left main stem or >70% stenosis in other coronary arteries | Ideally within 4 weeks of index presentation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Proportion of participants with moderate non-obstructive coronary artery disease | Proportion of participants with 50-70% stenosis in one or more coronary arteries | Ideally within 4 weeks of index presentation | 
| Proportion of participants with mild non-obstructive coronary artery disease | Proportion of participants with 10-50% stenosis in one or more coronary arteries | Ideally within 4 weeks of index presentation | 
| Proportion of participants with insignificant coronary artery disease | Proportion of participants with 1-10% stenosis in one or more coronary arteries | Ideally within 4 weeks of index presentation | 
| Proportion of participants with normal coronary arteries | Proportion of participants with no stenosis in coronary arteries | Ideally within 4 weeks of index presentation | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Coronary artery disease, CT coronary angiography, High-sensitivity cardiac troponin