Abstract 10843: Low Index of Microcirculatory Resistance Pre PCI Predicts Worsening Microvascular Function post PCI.
Background: Microvascular dysfunction following percutaneous coronary intervention (PCI) is known to be significantly associated with adverse outcome. Identification of pre-procedural factors which could predict those at risk could be valuable. Here we identify pre-procedural microvascular resistance as a novel potential marker for this.
Methods: We measured Fractional Flow Reserve (FFR), Coronary Flow Reserve (CFR) and Index of Microcirculatory Resistance (IMR) before and after PCI in patients with single vessel disease and stable angina. All haemodynamic data was acquired with a RADI pressure wire and the thermodilution technique. Measurements were performed at rest and at hyperaemia with intravenous adenosine 140μg/kg/min. The dependent variable was the degree of change in IMR in response to PCI, defined as IMR post PCI/IMR pre PCI.Univariate linear regression analysis was performed on the following variables to decide which variables to include in the multivariate model; pre PCI CRP, IL-6, Endothelin-1,FFR, IMR, Collateral flow index and length of lesion. All non normally distributed data was log transformed. Data is presented as mean+/−SEM or median [IQR].Statistical analysis was performed using paired t-test, Wilcoxon signed rank test and multivariate linear regression.
Results: 36 patients were included in the study. CFR and FFR increased in response to PCI respectively (1.96+/−0.22 vs. 2.67+/−0.24 p<0.001),(0.63+/−0.01 vs. 0.91+/−0.01 p<0.001). There was a heterogenous response of IMR following PCI with an increase in some patients and a reduction in others hence overall as a group there was no change in IMR (14.85[10.89–24.45] vs. 15.9[12.42–23.92] p=0.99).At multivariate linear regression analysis, only IMR pre PCI was independently associated with degree of change in IMR post PCI r=−0.73 r2=0.53 (y=3.38–1.16x p<0.001).
Conclusions: Subjects with very low IMR pre-PCI are those most at risk of microvascular dysfunction post PCI with an exaggerated increase in resistance. This may be due to the large increase in perfusion pressure resulting in microvascular vasoconstriction as a form of microcirculatory protection.
- © 2010 by American Heart Association, Inc.