Investigating the Utility of Remote Index of Microvascular Resistance in Patients With Chronic Total Occlusion

Study Overview
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Brief Summary
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This is prospective cohort study in subjects with a planned percutaneous coronary intervention (PCI) of their chronic total occlusion (CTO). The study will enroll subjects who have been scheduled for a clinically-indicated cardiac catheterization, and will evaluate coronary microvascular function in all subjects meeting inclusion criteria with a coronary flow wire. Evaluation of coronary microvascular function may be performed using indirect methods, however the rationale behind the present study is to directly measure microvascular function using direct coronary flow measurements, since the subjects in the study are to undergo a clinically-indicated cardiac catheterization. The overall purpose of the study is to define the presence and severity of coronary microvascular dysfunction subjects with CTO. The study is designed to enroll 50 subjects with CTO in the span of 3 years. There will be a 6-month assessment of the outcomes of death and cardiovascular death. As the study includes FDA approved tests, there will be no safety endpoint per se, however there will be a mechanism for monitoring adverse events as will be described in detail.

Official Title
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Investigating the Utility of Remote Index of Microvascular Resistance in Patients With Chronic Total Occlusion

Conditions
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Chronic Total Occlusion

Intervention / Treatment
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* Other: Directly measure microvascular function using direct coronary flow measurements


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: age ≥ 21 years seen at University of Chicago Medical center with a planned PCI of a single CTO vessel must have either stable angina or angina equivalent must have a CTO with a clear donor vessel supplying most of the collaterals. Exclusion Criteria: subjects with a pacemaker or implantable cardioverter defibrillator contraindication to cardiac MRI, adenosine, heparin, or nitroglycerin cardiac transplantation Estimated glomerular filtration rate (eGFR) ≤ 30 mL/min/1.73m2, given the risk of contrast-induced nephropathy (CIN) and nephrogenic systemic fibrosis (NSF) associated with iodinated and gadolinium-based contrast agents, respectively, in patients with significant renal dysfunction Women who may potentially be pregnant will receive a pregnancy test and be excluded if pregnant Vulnerable populations such as children, college students, prisoners, non-English speakers, and those with diminished decision-making capacity Inability or refusal to consent for the study.

Ages Eligible for Study
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Minimum Age: 21 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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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Subjects with Chronic Total Occlusion (CTO)<br>All subjects in this study have been scheduled for a clinically-indicated cardiac catheterization. | Other: Directly measure microvascular function using direct coronary flow measurements<br>* The study will enroll subjects who have been scheduled for a clinically-indicated cardiac catheterization, and will evaluate coronary microvascular function in all subjects meeting inclusion criteria with a coronary flow wire. Evaluation of coronary microvascular function may be performed using indirect methods, however the rationale behind the present study is to directly measure microvascular function using direct coronary flow measurements, since the subjects in the study are to undergo a clinically-indicated cardiac catheterization. The overall purpose of the study is to define the presence and severity of coronary microvascular dysfunction subjects with CTO.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Baseline myocardial quality of the CTO-supplied vascular bed. | Characterize the microvascular resistance of the donor vessel to 50 CTOs as it relates to vascular bed quality of the CTO-supplied territory. Scaled from 0-102, with 102 being worse than 0. 1. Baseline myocardial quality | Day of procedure | 
| IMR of opened CTO vessel | Following CTO PCI, IMR of the opened vessel will be measured. Scale is linear and 1-100 units, higher numbers being worse outcome. 3) Change in SAQ from baseline to 6 months | 6 months | 
| Change in exercise time on Bruce protocol baseline | Change in exercise time from baseline to 6 months post-PCI will be measured. Scale is linear and measured in seconds (can be a negative number), with higher numbers indicating a favorable outcome. | 6 months | 
| Change in SAQ from baseline to 6 months | Change in Seattle Angina Questionnaire (SAQ) from baseline to 6 months post-PCI will be measured. Scale is linear and 0-100 units, with higher numbers indicating a favorable outcome. | 6 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Microvascular Resistance, Percutaneous Coronary Intervention