Abbott Coronary Microvascular Dysfunction Algorithm

Catheter Engagement

(c)

• Flush thoroughly 1
• Coaxial guide engagement 1
• Ensure no damping1
  

(A)

Advance Wire

• Interrogate LAD unless there is a specific territory of interest 2
• Advance wire sensor 2/3 distally in vessel 3
•  Administer GTN/NTG1
  

(T)

Transit Time at Rest

• Flush/purge pre-Tmn rest to clear any blood and contrast 3
• Room temperature saline 3
• Brisk 3 mL x 3 injections 3
• Address outliers (± 0.25s) before proceeding 4*
  * Repeat measurement of Tmn rest
  

(H)

Hyperemic Transit Time

• Induce hyperemia 5
• Confirm hyperemia*6
• Flush/purge pre-Tmn hyp to clear any blood and contrast 6
• Room temperature saline 6
• Brisk 3 mL x 3 injections 6
• Address outliers (± 0.15s) before proceeding 4**
  * Decrease in pressure, patient symptoms, FFR drop *
  *Repeat measurement of Tmn hyp

(C)

Coronary Flow Reserve (CFR)

• CFR <2.5*4
• CFR grey zone 2.0-2.4*
  * Evolving consensus
  

(M)

Index of Microcirculatory Resistance (IMR)

• IMR ≥252
• Use IMRcorr if FFR ≤0.807
  

(D)

Diagnosis

• Diagnosis of CMD based on IMR ≥25 and CFR <2.5*2,4
• CFR grey zone 2.0-2.4*
• Refer to guidelines and consensus document2,4, 8-9
  * Evolving consensus
  

GTN (glyceryl trinitrate) |
NTG (nitroglycerin) |
LAD (left anterior descending) |
FFR (fractional flow reserve) |
IMRcorr (IMR corrected) |
CMD (coronary microvascular dysfunction) |
Tmnrest (resting transit mean time) |
Tmnhyp (hyperemic transit mean time)

References: 

1. Berry C. Fractional Flow Reserve, Coronary Flow Reserve and the Index of Microvascular Resistance in Clinical Practice. Radcliffe Cardiology. 2014, 1-6.
2. Kunadian V, et al. EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries. EHJ. 2020; 0, 1-21.
3. Fearon W, et al. Invasive Assessment of the Coronary Microvasculature: The Index of Microcirculatory Resistance. Circ Cardiovasc Interv. 2017; 10:e005361
4. Perera D, et al. Invasive coronary physiology in patients  with angina and non-obstructive coronary artery disease. Heart. 2022; 0, 1-8.
5. Ford T, et al. Stratified Medical Therapy Using Invasive Coronary Function Testing in Angina: The CorMicA Trial. JACC. 2018, 72, 2841-55.
6. Ang D, et al. Interventional Diagnostic Procedure: a Practical Guide for the Assessment of Coronary Vascular Function. JOVE 2022; 181, e2265.
7. Yong A, et al. Calculation of the Index of Microcirculatory Resistance Without Coronary Wedge Pressure Measurement in the Presence of Epicardial Stenosis. JACC: Cardiovasc Interv. 2013; 6, 53-8.
8. Knuuti J, et al. ESC guidelines. EHJ. 2020; 41, 407-477.
9. Gulati M, et al. 2021 Chest Pain Guideline, Circulation. 2021; 144, e368-e454.

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Documents / Resources

	Abbott Coronary Microvascular Dysfunction Algorithm [pdf] User Guide Coronary Microvascular Dysfunction Algorithm, Microvascular Dysfunction Algorithm, Dysfunction Algorithm, Algorithm
	Abbott Coronary Microvascular Dysfunction Algorithm [pdf] Instruction Manual Coronary Microvascular Dysfunction Algorithm, Microvascular Dysfunction Algorithm, Dysfunction Algorithm, Algorithm

References

• User Manual