Abstract 16029: Periprocedural Change of the Index of Microcirculatory Resistance in Patients Treated With Elective Stenting
BACKGROUND Recently, an index of microcirculatory resistance (IMR) was developed that is based on combined measurements of distal coronary pressure and thermodilution-derived mean transit time. This index has been reported to predict the severity of myocardial injury, myocardial viability, and LV recovery after primary stenting for AMI. However, whether this index can be used to predict PCI-related myocardial injury in patients undergoing elective stenting has not been determined.
METHODS AND RESULTS Thirty-five patients referred for non-emergency stenting underwent pre- and post-procedural IMR measurements. In vessels with a significant functional stenosis (FFR≤0.8), IMR was corrected by coronary wedge pressure to account for the influence of the collateral circulation. All patients showed normal preprocedural cardiac troponin I (cTnI) level. Serial cTnI measurements were performed after stenting. Clinical variables and IMR were compared between patients with (n = 11, 31%) and without (n = 24, 69%) post-PCI cTnI of >3 × upper reference limit (post-PCI myocardial infarction [MI]). Furthermore, the relationship between IMR and clinical/biochemical/ultrasound cardiographic (UCG) variables were assessed by Pearson's two-sided correlation coefficients. IMR, delta IMR (pre-procedural IMR - post-procedural IMR), and relative change in IMR were evaluated. Eighteen patients (51%) showed increased microvascular dysfunction and 17 patients (49%) showed reduced microvascular resistance after elective stenting. There was no significant correlation between any of the clinical/biochemical/UCG variables and IMR at baseline. There was no difference in any of three IMR measures between the two groups with or without post-PCI MI (IMR: median 16.4 (IQR 10.7 - 26.0) VS. 20.4 (17.8 - 40.0), delta IMR: 0.0 (-4.4 - 5.5) VS. 3.8(-8.1 - 17.5), relative change of IMR: -0.02 (-0.27 - 0.64) VS. 0.29 (-0.31 - 0.75), all p=ns). Furthermore, no significant relationship was found between post-PCI peak cTnI values and any of IMR measures. Post-procedural IMR showed significant relationship with pre-procedural IMR (r=0.43, p=0.01).
CONCLUSIONS IMR may not be a predictor of post-procedural microvascular dysfunction or myocardial injury after elective stenting.
- © 2011 by American Heart Association, Inc.