Exercise Metrics and Perfusion Indices in CoRonary Microvascular Dysfunction: A Multimodal Correlative Study in ANOCA and HFpEF Patients (EMPIRE-Trial)

November 8, 2026 updated by: Muhammed Gerçek, Heart and Diabetes Center North-Rhine Westfalia

Coronary microvascular dysfunction (CMD) has emerged as a key pathophysiological mechanism underlying symptoms in patients with angina and/or exertional dyspnea, particu-larly in the absence of obstructive coronary artery disease. CMD is prevalent in both ANOCA (Angina with Non-Obstructive Coronary Arteries) and HFpEF (Heart Failure with preserved Ejection Fraction), and is associated with poor clinical outcomes, including hospitalization and mortality. However, CMD remains frequently underdiagnosed due to the lack of simple, non-invasive diagnostic tools and the complexity of invasive assessment techniques such as the Index of Microcirculatory Resistance (IMR) and corrected Fractional Flow Reserve (cFR).

Cardiopulmonary exercise testing (CPET) and echocardiography are widely accessible and routinely used modalities that may reflect hemodynamic consequences of CMD. CPET pro-vides a comprehensive assessment of cardiopulmonary performance and exercise tolerance, while echocardiography allows for non-invasive evaluation of diastolic function, left atrial pressure, and right heart-pulmonary interactions. Nevertheless, the extent to which these measures correlate with invasive CMD parameters has not been systematically studied.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

120

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Germany
    • North Rhine-Westphalia
      • Bad Oeynhausen, North Rhine-Westphalia, Germany, 32545

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Age ≥ 18 years
  • Absence of obstructive coronary artery disease (stenosis <50% or FFR >0.80)
  • No sign of HFpEF or microvascular dysfunction history of angina, dyspnea, or heart failure
  • Undergoing CPET and echocardiography
  • No structural or ischemic heart disease
  • Written informed consent

Exclusion Criteria:

  • • Significant structural heart disease (e.g., severe valvular disease)

    • Severe pulmonary disease (e.g., COPD GOLD III-IV, interstitial lung disease)
    • Acute coronary syndrome within the past 3 months
    • Inability to perform exercise testing

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Other: patients with ANOCA or HFpEF

Patients with angina and/or exertional dyspnea without obstructive coronary artery disease (ANOCA or HFpEF phenotype).
Diagnostic test: All participants will undergo cardiopulmonary exercise testing (CPET), transthoracic echocardiography, and invasive coronary angiography with functional microvascular assessment (IMR, cFR, RFR). No in

This is a prospective, observational, controlled cohort study including patients with suspected coronary microvascular dysfunction (CMD) presenting as ANOCA or HFpEF and asymptomatic control individuals without evidence of coronary or myocardial disease, microvascular dysfunction or heart failure with preserved ejection fraction. All participants will undergo cardiopulmonary exercise testing (CPET), transthoracic echocardiography, and invasive coronary angiography with functional microvascular assessment (IMR, cFR, RFR). No interventions outside of standard clinical care will be performed. Comparative analyses will focus on correlations between CPET parameters, echocardiographic markers, and invasive microvascular indices, as well as differences between symptomatic patients and controls.

The study will include:

  • Patients with angina and/or exertional dyspnea without obstructive coronary artery disease (ANOCA or HFpEF phenotype).
  • Control individuals without evidence of coronary or my
Other: control participants

Control individuals without evidence of coronary or myocardial disease, microvascular dysfunction or heart failure with preserved ejection fraction
Diagnostic test: All participants will undergo cardiopulmonary exercise testing (CPET), transthoracic echocardiography, and invasive coronary angiography with functional microvascular assessment (IMR, cFR, RFR). No in

This is a prospective, observational, controlled cohort study including patients with suspected coronary microvascular dysfunction (CMD) presenting as ANOCA or HFpEF and asymptomatic control individuals without evidence of coronary or myocardial disease, microvascular dysfunction or heart failure with preserved ejection fraction. All participants will undergo cardiopulmonary exercise testing (CPET), transthoracic echocardiography, and invasive coronary angiography with functional microvascular assessment (IMR, cFR, RFR). No interventions outside of standard clinical care will be performed. Comparative analyses will focus on correlations between CPET parameters, echocardiographic markers, and invasive microvascular indices, as well as differences between symptomatic patients and controls.

The study will include:

  • Patients with angina and/or exertional dyspnea without obstructive coronary artery disease (ANOCA or HFpEF phenotype).
  • Control individuals without evidence of coronary or my

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation Between Peak Oxygen Uptake (VO₂peak) and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between peak oxygen uptake (VO₂peak), measured by cardiopulmonary exercise testing (CPET), and the index of microcirculatory resistance (IMR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Peak Oxygen Uptake (VO₂peak) and CFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between peak oxygen uptake (VO₂peak), measured by cardiopulmonary exercise testing (CPET), and CFR, assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Peak Oxygen Uptake (VO₂peak) and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between peak oxygen uptake (VO₂peak), measured by cardiopulmonary exercise testing (CPET), and resting full-cycle ratio (RFR), assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between VE/VCO₂ Slope and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the ventilatory efficiency parameter VE/VCO₂ slope, measured by cardiopulmonary exercise testing (CPET), and the index of microcirculatory resistance (IMR), assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between VE/VCO₂ Slope and CFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the ventilatory efficiency parameter VE/VCO₂ slope, measured by cardiopulmonary exercise testing (CPET), and CFR, assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between VE/VCO₂ Slope and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the ventilatory efficiency parameter VE/VCO₂ slope, measured by cardiopulmonary exercise testing (CPET), and resting full-cycle ratio (RFR), assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Oxygen Pulse and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between oxygen pulse (O₂ pulse), measured by cardiopulmonary exercise testing (CPET), and the index of microcirculatory resistance (IMR), assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Oxygen Pulse and CFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between oxygen pulse (O₂ pulse), measured by cardiopulmonary exercise testing (CPET), and cFR, assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Oxygen Pulse and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between oxygen pulse (O₂ pulse), measured by cardiopulmonary exercise testing (CPET), and resting full-cycle ratio (RFR), assessed during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Correlation Between E/e' Ratio and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the echocardiographically assessed E/e' ratio, a marker of left ventricular filling pressure, and the index of microcirculatory resistance (IMR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between E/e' Ratio and cFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the echocardiographically assessed E/e' ratio and cFR, measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between E/e' Ratio and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the echocardiographically assessed E/e' ratio and resting full-cycle ratio (RFR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Left Atrial Volume Index (LAVI) and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between left atrial volume index (LAVI), assessed by transthoracic echocardiography and expressed in mL/m², and the index of microcirculatory resistance (IMR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Left Atrial Volume Index (LAVI) and cFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between left atrial volume index (LAVI), assessed by transthoracic echocardiography and expressed in mL/m², and cFR, measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between Left Atrial Volume Index (LAVI) and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between left atrial volume index (LAVI), assessed by transthoracic echocardiography and expressed in mL/m², and resting full-cycle ratio (RFR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between TAPSE/PASP Ratio and Index of Microcirculatory Resistance (IMR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the ratio of tricuspid annular plane systolic excursion to pulmonary artery systolic pressure (TAPSE/PASP), assessed by transthoracic echocardiography as an index of right ventricular-pulmonary arterial coupling, and the index of microcirculatory resistance (IMR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between TAPSE/PASP Ratio and cFR
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the echocardiographically assessed TAPSE/PASP ratio, an index of right ventricular-pulmonary arterial coupling, and cFR, measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Correlation Between TAPSE/PASP Ratio and Resting Full-Cycle Ratio (RFR)
Time Frame: Baseline (during the initial diagnostic assessment)

Correlation between the echocardiographically assessed TAPSE/PASP ratio, an index of right ventricular-pulmonary arterial coupling, and resting full-cycle ratio (RFR), measured during invasive coronary angiography. The association will be quantified using Pearson's or Spearman's correlation coefficient, as appropriate. The correlation coefficient is dimensionless.
Baseline (during the initial diagnostic assessment)
Number of Distinct Coronary Microvascular Dysfunction Phenotypes Identified by Cluster Analysis
Time Frame: Baseline (during the initial diagnostic assessment)

Number of distinct phenotypic clusters identified among symptomatic patients with ANOCA or HFpEF using unsupervised cluster analysis of baseline cardiopulmonary exercise testing parameters, echocardiographic markers, and invasive coronary physiological indices.
Baseline (during the initial diagnostic assessment)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Heart and Diabetes Center North-Rhine Westfalia

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

August 11, 2025

Primary Completion (Estimated)

June 1, 2029

Study Completion (Estimated)

June 1, 2029

Study Registration Dates

First Submitted

August 11, 2025

First Submitted That Met QC Criteria

November 8, 2026

First Posted (Actual)

November 12, 2026

Study Record Updates

Last Update Posted (Actual)

November 12, 2026

Last Update Submitted That Met QC Criteria

November 8, 2026

Last Verified

November 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • HDZ-KA_0525_EMPIRE

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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