Abstract 17172: Variability of Index of Microcirculatory Resistance in Patients with Intermediate Coronary Artery Lesions
Background: Although atherosclerosis affects both epicardial coronary arteries and microvasculatures, the relationship between functional significance of epicardial coronary artery stenosis and microvascular resistance remains to be determined in vessels with intermediate lesions. Furthermore, little is known regarding the determinants of microvascular resistance in patients with intermediate coronary lesions.
Methods and Results: Using a pressure-temperature sensor-tipped guidewire, thermodilution-derived index of microcirculatory resistance (IMR) was measured, along with fractional flow reserve (FFR), in 131 coronary arteries of 104 patients with de novo single discrete intermediate stenosis. We sought to determine the relationship between IMR values and clinical and demographic data. IMR showed a large variability (median 20.8, IQR 13.0 to 30.5, range 6.3 to 65.2) and no significant relationship was observed between IMR and FFR after IMR values were corrected for coronary wedge pressure in the territories with functionally significant stenoses. There was no significant relationship between IMR and clinically based risk scores of Framingham risk score snd SCORE (Systematic Coronary Risk Score). IMR also showed no significant association with anatomy-based risk scores of the study vessel including ACC/AHA lesion classification and SYNTAX score. RCA lesion location and history of hypertension (HT) were significantly associated with increased IMR (> median value). In multivariate analysis, factors independently associated with increased IMR were RCA lesion location (odds ratio (OR) 4.60, 95% confidence interval (CI) 1.85 to 11.41, p=0.001), HT (OR 3.97, 95% CI 1.46 to 10.78, p=0.007) and triglyceride (OR 0.99, 95% CI 0.98 to 0.99, p=0.023). The Hosmer and Lemeshow test provided P values of 0.356, which indicated a proper goodness of fit.
Conclusions: Functional significance of intermediate coronary stenosis was not correlated with microvascular resistance of the perfusion territory. A significant number of patients present increased microcirculatory resistance irrespective of functional significance of the stenoses. There seems to be a significant regional difference in microvascular resistance.
- © 2012 by American Heart Association, Inc.