Prognostic value of the Index of Microcirculatory Resistance measured after primary percutaneous coronary intervention

William F. Fearon*, Adrian F. Low, Andy S. Yong, Ross McGeoch, Colin Berry, Maulik G. Shah, Michael Y. Ho, Hyun Sook Kim, Joshua P. Loh, Keith G. Oldroyd

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

210 Citations (Scopus)

Abstract

Background: Most methods for assessing microvascular function are not readily available in the cardiac catheterization laboratory. The aim of this study is to determine whether the Index of Microcirculatory Resistance (IMR), measured at the time of primary percutaneous coronary intervention, is predictive of death and rehospitalization for heart failure. Methods and Results: IMR was measured immediately after primary percutaneous coronary intervention in 253 patients from 3 institutions with the use of a pressure-temperature sensor wire. The primary end point was the rate of death or rehospitalization for heart failure. The prognostic value of IMR was compared with coronary flow reserve, TIMI myocardial perfusion grade, and clinical variables. The mean IMR was 40.3±32.5. Patients with an IMR >40 had a higher rate of the primary end point at 1 year than patients with an IMR ≥40 (17.1% versus 6.6%; P=0.027). During a median follow-up period of 2.8 years, 13.8% experienced the primary end point and 4.3% died. An IMR >40 was associated with an increased risk of death or rehospitalization for heart failure (hazard ratio [HR], 2.1; P=0.034) and of death alone (HR, 3.95; P=0.028). On multivariable analysis, independent predictors of death or rehospitalization for heart failure included IMR >40 (HR, 2.2; P=0.026), fractional flow reserve ≤0.8 (HR, 3.24; P=0.008), and diabetes mellitus (HR, 4.4; P<0.001). An IMR >40 was the only independent predictor of death alone (HR, 4.3; P=0.02). Conclusions: An elevated IMR at the time of primary percutaneous coronary intervention predicts poor long-term outcomes.

Original languageEnglish
Pages (from-to)2436-2441
Number of pages6
JournalCirculation
Volume127
Issue number24
DOIs
Publication statusPublished - 18 Jun 2013
Externally publishedYes

Keywords

  • Microcirculation
  • Myocardial infarction
  • Physiology

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