Coronary Flow During Rapid Heart Rates

Study Overview
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Brief Summary
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The goal of this observational study is to learn about the factors which determine how well ventricular tachycardia (VT) is tolerated. The main questions it aims to answer are: What impact does coronary artery disease have on the ability for a patient to tolerate VT? Does treatment of coronary artery disease with stents improve the tolerability of VT? Participants who are undergoing a clinically indicated coronary angiogram or coronary angioplasty procedure will have measurements of blood pressure, coronary pressure and coronary flow made during pacing at a range of heart rates.

Detailed Description
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Ventricular tachycardia (VT) is a common and life-threatening arrhythmia that occurs in people with heart problems. Some patients who develop this arrhythmia remain very stable with very little symptoms while others become unstable with low blood pressure or even sudden death. It is not known why some people tolerate the arrhythmia well and others do not. If VT is not tolerated then current practice is to offer an implantable cardioverter defibrillator (ICD) which can deliver a shock to the heart if dangerous heart rhythms are detected. While shocks can be life-saving, they are also harmful, including causing psychological distress. ICDs also frequently deliver shocks when they are not needed. If research could identify which factors predispose a person to be stable or unstable in VT, this would allow doctors to help them in a range of ways. One way would be to treat patients to improve the tolerance of VT, so avoiding the need for an ICD. Another would be to assess the the risk of instability and so allow a patient-centred decision on whether an ICD is needed. In this study the investigators plan to recruit patients who are referred for a coronary angiogram. During the angiogram, the investigators will stimulate the heart at a range of fast heart rates and measure their blood pressure and flow in their coronary arteries. In patients who undergo stenting for a coronary stenosis, the investigators will also make these measurements after stenting so they can see if there is any difference. By recruiting a range of different cardiology patients, the investigators will be able to assess which factors contribute to stability during VT.

Official Title
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Coronary Epicardial and Microcirculatory Determinants of Ventricular Tachycardia Tolerability

Conditions
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Heart Failure, Ventricular Tachycardia, Coronary Artery Disease, Coronary Microvascular Dysfunction, Coronary Microvascular Disease

Intervention / Treatment
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* Diagnostic Test: Pressure and flow measurement during simulated VT


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Able to give valid consent Referred for coronary angiography or coronary angioplasty Suitable for percutaneous physiological interrogation and PCI when clinically indicated Exclusion Criteria: Unable to give valid consent Pregnant or breastfeeding women Unstable coronary artery disease (acute coronary syndrome) Severe multivessel coronary artery disease suitable for coronary artery bypass grafting Severe heart valve disease Severe (NYHA IV) heart failure

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 |
| --- | --- |
| Controls<br>10 patients with unobstructed coronary arteries, normal microvascular function and normal LV function. | Diagnostic Test: Pressure and flow measurement during simulated VT<br>* Participants undergoing coronary angiography will have measurements of blood pressure, coronary pressure and coronary flow during simulated VT. VT will be simulated using pacing at a range of heart rates.<br>|
| Coronary artery disease<br>25 patients with severe, single-vessel coronary artery disease of the proximal LAD or proximal other dominant vessel awaiting PCI. | Diagnostic Test: Pressure and flow measurement during simulated VT<br>* Participants undergoing coronary angiography will have measurements of blood pressure, coronary pressure and coronary flow during simulated VT. VT will be simulated using pacing at a range of heart rates.<br>|
| Microvascular dysfunction<br>15 patients with without severe disease in any coronary artery, impaired microvascular function and normal LV function. | Diagnostic Test: Pressure and flow measurement during simulated VT<br>* Participants undergoing coronary angiography will have measurements of blood pressure, coronary pressure and coronary flow during simulated VT. VT will be simulated using pacing at a range of heart rates.<br>|
| Heart failure<br>20 patients with LV systolic dysfunction (LVEF<40%). | Diagnostic Test: Pressure and flow measurement during simulated VT<br>* Participants undergoing coronary angiography will have measurements of blood pressure, coronary pressure and coronary flow during simulated VT. VT will be simulated using pacing at a range of heart rates.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in coronary flow in participants with different levels of coronary microvascular function. |  | At baseline and during simulated VT | 
| Change in coronary flow in participants immediately before and after PCI |  | At baseline and during simulated VT, immediately before PCI and after PCI | 
| Change in blood pressure in participants with different levels of coronary microvascular function. |  | At baseline and during simulated VT | 
| Change in blood pressure in participants before and after PCI |  | At baseline and during simulated VT, immediately before PCI and after PCI | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in coronary flow in participants with different levels of left ventricular function |  | At baseline and during simulated VT | 
| Change in blood pressure in participants with different levels of left ventricular function |  | At baseline and during simulated VT | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ventricular Tachycardia, Coronary Artery Disease, Heart Failure, Coronary Microvascular Dysfunction, Coronary Microvascular Disease, Percutaneous Coronary Intervention, Implantable Cardioverter Defibrillator