Angio-IMR and Cardiac MR-derived MVO in STEMI Patients

Functional Coronary Angiography-Derived Index of Microcirculatory Resistance and Microvascular Obstruction in Cardiac Magnetic Resonance Imaging After ST-segment Elevation Myocardial Infarction

Coronary microcirculatory dysfunction has been known to be prevalent even after successful revascularization of ST-segment elevation myocardial infarction (STEMI) patients. Microvascular obstruction (MVO) in cardiac magnetic resonance (CMR) is significant prognostic indicator in STEMI patients after primary percutaneous coronary intervention (PCI). Although current gold-standard method to assess microvascular damage or dysfunction in STEMI patients is CMR and assessment of MVO, previous study presented that index of microcirculatory resistance (IMR) in culprit vessel of STEMI patients showed significant association with the presence of MVO in CMR and the risk of cardiac death or heart failure admission. Nevertheless, the need for pressure-temperature sensor wire and hyperemic agents significantly limits adoption of IMR in daily practice.

Recent technical development enabled angiographic derivation of IMR without pressure wire, hyperemic agents, or thermodilution method. In this regard, the current study will evaluate the feasibility of functional angiography-derived IMR (angio-IMR) in the evaluation of MVO after successful primary PCI for STEMI.

Study Overview

• Status: Completed
• Conditions: ST-segment Elevation Myocardial Infarction (STEMI)
• Intervention / Treatment: Diagnostic test: Cardiac magnetic resonance imaging

Detailed Description

Coronary microcirculatory dysfunction has been known to be prevalent even after successful revascularization of ST-segment elevation myocardial infarction (STEMI) patients. Microvascular obstruction (MVO) in cardiac magnetic resonance (CMR) is significant prognostic indicator in STEMI patients after primary percutaneous coronary intervention (PCI). Although current gold-standard method to assess microvascular damage or dysfunction in STEMI patients is CMR and assessment of MVO, previous study presented that index of microcirculatory resistance (IMR) in culprit vessel of STEMI patients showed significant association with the presence of MVO in CMR and the risk of cardiac death or heart failure admission. Nevertheless, the need for pressure-temperature sensor wire and hyperemic agents significantly limits adoption of IMR in daily practice.

Recent technical development enabled angiographic derivation of IMR without pressure wire, hyperemic agents, or thermodilution method. In this regard, the current study will evaluate the feasibility of functional angiography-derived IMR (angio-IMR) in the evaluation of MVO after successful primary PCI for STEMI.

The study population will be derived from the prospective institutional AMI registry of Samsung Medical Center between December 2007 and July 2014. Main results from this registry were published elsewhere (PLoS One. 2017 Jan 12;12(1):e0170115 and Sci Rep. 2019 Jul 4;9(1):9646). In this registry, 515 consecutive patients who presented with acute myocardial infarction and underwent CMR were prospectively enrolled. AMI was defined as evidence of myocardial injury (defined as elevation of cardiac troponin values, with at least one value above the 99th percentile upper reference limit) with necrosis in a clinical setting, consistent with myocardial ischemia. Among the total patients, STEMI patients (n = 332), whose electrocardiogram showed ST-segment elevation more than 1 mm in two or more contiguous leads or a presumably new-onset left bundle branch block, will be analyzed for the current study. For the study purpose, patients with failed primary PCI (n=1), treated by medical treatment alone without PCI (n=4), and no available coronary angiographic images (n=3) will be excluded. Among the remaining 324 patients, functional coronary angiography core laboratory (Shanghai Institute of Cardiovascular Diseases, Shanghai, China) evaluated the quality of angiographic images and additionally exclude patients with insufficient image quality for angio-IMR calculation (n=37). All patients also underwent baseline and 1-year follow-up echocardiography. The Institutional Review Board of Samsung Medical Center approved this study, and all patients provided written informed consent.

The association of Angio-IMR with CMR-derived quantitative parameters (extent of MVO, infarct size, area at risk) and qualitative parameter (presence of MVO) will be analyzed. The discrimination ability of angio-IMR to predict the presence of MVO in CMR will be compared with conventional angiographic measures of culprit vessel reperfusion (TIMI flow grade, myocardial blush grade).

• Study Type: Observational
• Enrollment (Actual): 324

Contacts and Locations

Study Locations

• China
  • Shanghai
    • Shanghai, Shanghai, China
      • Shanghai Institute of Cardiovascular Diseases, Shanghai, China
• United States
  • Iowa
    • Iowa City, Iowa, United States
      • University of Iowa Carver College of Medicine, Iowa City, IA, USA

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

The study population will be derived from the prospective institutional AMI registry of Samsung Medical Center between December 2007 and July 2014. In this registry, 515 consecutive patients who presented with acute myocardial infarction and underwent CMR were prospectively enrolled. Among the total patients, STEMI patients (n = 332) will be analyzed for the current study. For the study purpose, patients with failed primary PCI (n=1), treated by medical treatment alone without PCI (n=4), and no available coronary angiographic images (n=3) will be excluded. Among the remaining 324 patients, patients with insufficient image quality for angio-IMR calculation will be additionally excluded (n=37).

Description

Inclusion Criteria:

• STEMI patients
• Successful primary PCI in the culprit vessel
• Underwent cardiac MR during index hospitalization
• Suitable coronary angiographic images for angio-IMR analysis

Exclusion Criteria:

• patients with failed primary PCI
• treated by medical treatment alone without PCI
• no available coronary angiographic images
• insufficient image quality for angio-IMR calculation

Study Plan

How is the study designed?

Design Details

• Observational Models: Cohort
• Time Perspectives: Prospective

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Patients with Angio-IMR>40 Unit; Patients with angio-IMR>40U in the culprit vessel after successful primary PCI.	Diagnostic test: Cardiac magnetic resonance imaging; Cardiac magnetic resonance imaging was performed 5.0 ± 5.8 days after the primary PCI. MVO, infarct size, and myocardial salvage index were quantitatively assessed in CMR.
Patients with Angio-IMR≤40 Unit; Patients with angio-IMR≤40U in the culprit vessel after successful primary PCI.	Diagnostic test: Cardiac magnetic resonance imaging; Cardiac magnetic resonance imaging was performed 5.0 ± 5.8 days after the primary PCI. MVO, infarct size, and myocardial salvage index were quantitatively assessed in CMR.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of microvascular obstruction in CMR	Proportion of microvascular obstruction in CMR	At the time of index hospitalization

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Correlation of angio-IMR with the extent of microvascular obstruction in CMR	Correlation of angio-IMR with the extent of microvascular obstruction (% of left ventricular mass) in CMR	At the time of index hospitalization
Correlation of angio-IMR with the infarct size in CMR	Correlation of angio-IMR with the infarct size (% of left ventricular mass) in CMR	At the time of index hospitalization
Correlation of angio-IMR with the area at risk in CMR	Correlation of angio-IMR with the area at risk (% of left ventricular mass) in CMR	At the time of index hospitalization
Correlation of angio-IMR with the myocardial salvage index in CMR	Correlation of angio-IMR with the myocardial salvage index in CMR	At the time of index hospitalization
Discrimination ability of angio-IMR to predict the occurrence of microvascular obstruction in CMR	area under curve in ROC analysis of angio-IMR to predict the occurrence of microvascular obstruction in CMR	At the time of index hospitalization
Left ventricular ejection fraction	Left ventricular ejection fraction in echocardiography	At the time of index hospitalization and 1 year follow-up
Regional wall motion score index	Regional wall motion score index in echocardiography	At the time of index hospitalization and 1 year follow-up

Collaborators and Investigators

• Sponsor: Samsung Medical Center
• Collaborators: RainMed Medical; Shanghai Institute of Cardiovascular Diseases
• Investigators: Principal Investigator: Joo Myung Lee, MD, MPH, PhD, Samsung Medical Center

Publications and helpful links

General Publications

• Shin D, Kim J, Choi KH, Dai N, Li Y, Lee SH, Joh HS, Kim HK, Kim SM, Ha SJ, Jang MJ, Park TK, Yang JH, Song YB, Hahn JY, Choi SH, Choe YH, Gwon HC, Lee JM. Functional angiography-derived index of microcirculatory resistance validated with microvascular obstruction in cardiac magnetic resonance after STEMI. Rev Esp Cardiol (Engl Ed). 2022 Oct;75(10):786-796. doi: 10.1016/j.rec.2022.01.004. Epub 2022 Mar 3. English, Spanish.

Study record dates

Study Major Dates

• Study Start (Actual): December 24, 2007
• Primary Completion (Actual): December 31, 2021
• Study Completion (Actual): December 31, 2023

Study Registration Dates

• First Submitted: March 30, 2021
• First Submitted That Met QC Criteria: March 30, 2021
• First Posted (Actual): April 2, 2021

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: March 12, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: Coronary microcirculation; Microvascular obstruction; Index of microcirculatory resistance; Cardiac magnetic resonance imaging; ST-segment Elevation Myocardial Infarction (STEMI)
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Pathologic Processes; Heart Diseases; Necrosis; Myocardial Ischemia; Ischemia; ST Elevation Myocardial Infarction; Myocardial Infarction; Infarction
• Other Study ID Numbers: SMCCMR88848439

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: IPD will be able to be shared upon reasonable request after discussion by steering committee members and principal investigator.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No