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Coronary microcirculatory resistance is independent of epicardial stenosis

Andy S C Yong1, Michael Ho, Maulik G Shah

  • 1Division of Cardiovascular Medicine, Stanford University Medical Center, Stanford, CA 94305, USA.

Circulation. Cardiovascular Interventions
|February 3, 2012
PubMed

Insights

Coronary microcirculatory resistance, measured accurately accounting for collateral flow, is not dependent on epicardial stenosis severity. This finding clarifies the relationship between microvascular function and epicardial disease in cardiovascular patients.

Area of Science:

  • Cardiology
  • Cardiovascular Physiology
  • Interventional Cardiology

Background:

  • Coronary microcirculatory impairment predicts poor cardiovascular outcomes.
  • The relationship between microcirculatory resistance and epicardial stenosis severity is debated.
  • Previous studies may have underestimated microcirculatory resistance by not accounting for collateral flow.

Purpose of the Study:

  • To determine if the index of microcirculatory resistance (IMR) is independent of epicardial stenosis severity.
  • To compare IMR measurements before and after percutaneous coronary intervention (PCI).

Main Methods:

  • Recruited patients undergoing elective PCI of the left anterior descending artery.
  • Measured apparent IMR (IMR(app)) and true IMR (IMR(true)) using a pressure-temperature sensor wire before and after PCI.
  • IMR(true) accounts for collateral flow via wedge pressure measurement, unlike IMR(app).

Main Results:

  • No significant difference in IMR(true) was observed before and after PCI (P=0.675).
  • IMR(app) was significantly higher before PCI compared to after PCI (P<0.001).
  • IMR(app) was consistently higher than IMR(true), with the difference increasing as fractional flow reserve decreased and coronary wedge pressure increased.

Conclusions:

  • Coronary microcirculatory resistance, when adjusted for collateral flow, is independent of epicardial stenosis severity.
  • Accurate assessment of microcirculatory resistance requires accounting for collateral circulation.
Abstract

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