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Coronary physiology thresholds associated with microvascular obstruction in myocardial infarction

Stefano Benenati1,2, Matteo Montorfano3, Silvia Pica4

  • 1Cardiovascular Disease Chair, Department of Internal Medicine (Di.M.I.), University of Genova, Genova, Liguria, Italy.

Heart (British Cardiac Society)
|October 25, 2023
PubMed

Insights

Invasive assessment of coronary flow reserve (CFR) and index of microvascular resistance (IMR) can identify microvascular obstruction after ST-elevation myocardial infarction (STEMI). Patients with high IMR and low CFR show worse outcomes, including larger infarct size.

Area of Science:

  • Cardiology
  • Cardiovascular Research
  • Interventional Cardiology

Background:

  • ST-segment elevation myocardial infarction (STEMI) requires prompt treatment to restore blood flow.
  • Microvascular obstruction can occur despite successful reperfusion, impacting patient outcomes.
  • Assessing coronary physiology post-intervention is crucial for risk stratification.

Purpose of the Study:

  • To evaluate the association between invasive coronary physiology assessment and microvascular obstruction in STEMI patients.
  • To determine optimal cut-off values for index of microvascular resistance (IMR) and coronary flow reserve (CFR) in predicting microvascular obstruction.
  • To compare novel stratification models with existing ones.

Main Methods:

  • Prospective enrollment of 102 STEMI patients across five Italian tertiary centers (November 2020 - December 2021).
  • Measurement of CFR and IMR in the culprit vessel immediately after primary percutaneous coronary intervention.
  • Stratification of patients into four groups based on optimal IMR and CFR cut-off points.

Main Results:

  • Optimal cut-off points identified as IMR > 31 units and CFR ≤ 1.25.
  • Patients with IMR > 31 and CFR ≤ 1.25 had significantly higher microvascular obstruction (83% vs 38%, p<0.001) and lower ejection fraction (45±9% vs 52±9%, p=0.043).
  • This high-risk group also exhibited larger infarct size and area at risk compared to other groups.

Conclusions:

  • IMR and CFR are reliable indicators of microvascular obstruction in STEMI.
  • An IMR > 31 units and CFR ≤ 1.25 identifies STEMI patients at high risk for adverse outcomes.
  • These physiological parameters aid in risk stratification and management decisions post-PCI.
Abstract

Keywords:
Acute Coronary SyndromeCardiac CatheterizationMagnetic Resonance ImagingPercutaneous Coronary Intervention

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