Coronary Microvascular Dysfunction (CMD)

Go Beyond the Angiogram to Get to the Root Cause of Persistent Angina

Coronary Microvascular Dysfunction (CMD)

How to Diagnose INOCA

The European Association of Percutaneous Cardiovascular Interventions (EAPCI) Expert Consensus Document defines ischemia and no obstructive coronary artery disease (INOCA) and guidance to its diagnosis and management. The document states that, INOCA patients present with a wide spectrum of symptoms and signs that are often misdiagnosed as non-cardiac, leading to under-diagnosis/investigation and under-treatment.1

Ischemia with non-obstructive coronary arteries graphic

Guidelines Recommend Guidewire-Based Measurements

Both European and American guidelines provide a class IIa recommendation for a physiology wire-based assessment for patients with stable chest pain and/or Ischemia and No Obstructive Coronary Artery Disease (INOCA).2,3

The ESC guidelines2 2019 were updated accordingly to include an increased focus on microvascular dysfunction.

Guidelines Recommend Guidewire-Based Measurements

The AHA/ACC Clinical Practice Guideline3 on chest pain includes Class IIa recommendation for guidewire-based assessment for ischemia and no obstructed coronary artery disease (INOCA) patients.

Recommendations for patients with INOCA

CFR = coronary flow reserve; CMR = cardiac magnetic resonance; ECG = electrocardiogram;
FFR = fractional flow reserve; iwFR = instantaneous wave-free ratio; LAD = left anterior descending; PET = position emission tomography.

a Class of recommendation

b Level of evidence

Level-NR: Level (Quality) of Evidence Level B-NR (non-randomized): moderate-quality evidence from 1 or more well-designed, well-executed non-randomized studies, observational studies or registry studies. RCTs. Meta-analyses of such studies.

INOCA is Not Benign: Coronary Microvascular Dysfunction — Why Diagnosis In the Cath Lab Does Matter

The spectrum of coronary artery disease


Aladie Chieffo MD, Milan, Italy

An updated standardization of Coronary Microvascular Dysfunction (CMD) criteria is provided by the COVADIS group including the cut-off values of CFR < 2.0 and IMR ≥ 25 that characterize CMD.1

CriteriaEvidenceDiagnostic Parameters

Symptoms of myocardial ischaemiaa

  • Effort or rest angina
  • Exertional dyspnoea

Absence of obstructive CAD (<50% diameter reduction or FFR >0.80)

  • Coronary CTA
  • Invasive coronary angiography

Objective evidence of myocardial ischaemiab

  • Presence of reversible defect, abnormality or flow reserve on a functional imaging test

Evidence of impaired coronary microvascular function

  • Impaired coronary flow reserve (cut-off <2.0), invasive or noninvasively determined
  • Coronary microvascular spasm, defined as reproduction of symptoms, ischaemic ECG shifts but no epicardial spasm during acetylcholine testing
  • Abnormal coronary microvascular resistance indices (e.g. IMR ≥25)


Kunadian et al. European Heart Journal. 2020; 0:1-21.

Definitive microvascular angina is only diagnosed if criterias 1, 2, 3 and 4 are present.

CAD = coronary artery disease; CCTA = coronary computed tomographic angiography; CFR = coronary flow reserve; ECG = electrocardiogram; FFR = fractional flow reserve; IMR = index of microcirculatory resistance.

a Many patients with heart failure with preserved ejection fraction would fulfil these criteria: dyspnoea, no obstructive CAD and impaired CFR. For this reason, consider measuring LV end-diastolic pressure (normal ≤10 mmHg) and NT-proBNP normal <125 pg/mL.

b Signs of ischaemia may be present but are not necessary. However, evidence of impaired coronary microvascular function should be present.

How to Diagnose CMD with a Comprehensive Physiology Assessment

The PressureWire™ X Guidewire and CoroFlow Cardiovascular System is a comprehensive solution for assessing both epicardial arteries and the microvasculature.4

How to Measure IMR

How to Measure IMR

Allen Jeremias, MD, New York, USA

Diagnosis in the cath lab

 Diagnosis With Comprehensive Physiology Indices

Colin Berry MD, PhD, Glasgow, UK

The PressureWire™ X Guidewire has pressure and temperature sensors that communicate with the CoroFlow Cardiovascular System to provide a comprehensive physiology assessment4

Pressure and temperature sensors

How to Treat Patients with CMD: Results of the CorMicA Trial

Microvascular angina and vasospastic angina are the two most common causes of INOCA, and both types of angina can be identified with diagnostic testing. The randomized CorMicA trial provides a diagnostic and treatment approach.5

The trial protocol assessed patients to determine:

CorMicA Findings Video

CorMicA Findings

Colin Berry MD, PhD, Glasgow, UK

The CorMicA results indicate a role for a more thorough investigation of coronary microvascular dysfunction among patients with INOCA, as well as an opportunity to better tailor patient treatment.5

CorMicA Trial 1-year RCT Outcomes5

CorMicA Trial 1-year RCT Outcomes


The EAPCI Expert Consensus Document1 defines INOCA and provides guidance to the clinical community on the diagnostic approach and management of INOCA based on existing evidence and best current practices.

Management of INOCA

Angiotensin-converting enzyme inhibitor = ACEI
Angiotensin receptor blocker = ARB


  1. Kunadian, V., et al. EAPCI Expert Consensus. Eur Heart J 2020;0:1-21.
  2. Knuuti, J., et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. European Heart Journal 2020:41,407-477.
  3. Gulati, M., et al. 2021 AHA/ACC Guideline for the Evaluation and Diagnosis of Chest Pain. Circulation 2021;144e368-e454.
  4. PressureWire X Guidewire Instructions for Use (IFU). Refer to IFUs for additional information. CoroFlow Cardiovascular System IFU.
  5. Ford, TJ., et al. 1-year outcomes of angina management guided by invasive coronary function testing (CorMicA). J Am Coll Cardiol Intv. 2020;13:33-45.

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