title: The index of microcirculatory resistance predicts myocardial infarction related to percutaneous coronary intervention.
abstract: BACKGROUND
  Periprocedural myocardial infarction (MI) occurs in a significant proportion of patients undergoing percutaneous coronary intervention (PCI) and portends poor outcomes. Currently, no clinically applicable method predicts periprocedural MI in the cardiac catheterization laboratory before it occurs. We hypothesized that impaired baseline coronary microcirculatory reserve, which reduces the ability to tolerate ischemic insults, is a risk for periprocedural MI and that the index of microcirculatory resistance (IMR) measured during PCI can predict occurrence of periprocedural MI.
  
  
  RESULTS
  Consecutive patients undergoing elective PCI of a single lesion in the left anterior descending coronary artery were recruited. A pressure-temperature sensor wire was used to measure IMR before PCI. Of the 50 patients studied, 10 had periprocedural MI. From binary logistic regression analyses of all clinical, procedural, and physiological parameters, univariable predictors of periprocedural MI were pre-PCI IMR (P=0.003) and the number of stents used (P=0.039). Pre-PCI IMR was the only independent predictor in bivariable regression analyses performed by adjusting for each available covariate one at a time (all P≤0.02). Pre-PCI IMR ≥27 U had 80.0% sensitivity and 85.0% specificity for predicting periprocedural MI (C statistic, 0.80; P=0.003). Pre-PCI IMR ≥27 U was independently associated with a 23-fold risk of developing periprocedural MI (odds ratio, 22.7; 95% CI, 3.8-133.9).
  
  
  CONCLUSIONS
  These data suggest that the status of the coronary microcirculation plays a role in determining susceptibility toward periprocedural MI at the time of elective PCI. The IMR can predict subsequent risk of developing myocardial necrosis and may guide adjunctive prevention strategies.
authors.affiliation: Department of Cardiology, Royal Prince Alfred Hospital, University of Sydney, Sydney, Australia.
authors.forename: Martin K C
authors.initials: MK
authors.lastname: Ng
authors.forename: Andy S C
authors.initials: AS
authors.lastname: Yong
authors.forename: Michael
authors.initials: M
authors.lastname: Ho
authors.forename: Maulik G
authors.initials: MG
authors.lastname: Shah
authors.forename: Chirapan
authors.initials: C
authors.lastname: Chawantanpipat
authors.forename: Rachel
authors.initials: R
authors.lastname: O'Connell
authors.forename: Anthony
authors.initials: A
authors.lastname: Keech
authors.forename: Leonard
authors.initials: L
authors.lastname: Kritharides
authors.forename: William F
authors.initials: WF
authors.lastname: Fearon
mesh_terms: D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000009:adverse effects*; D015897:Comorbidity; D017023:Coronary Angiography / Q000379:methods; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000628:therapy*; D003326:Coronary Circulation / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000209:etiology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D012307:Risk Factors