Abstract 15310: Intracoronary Doppler Flow Velocity and Pressure Derived Hyperemic Microvascular Resistance is Independent of Epicardial Obstruction in Stable Coronary Artery Disease
Introduction: Coronary microvascular function can be assessed invasively by combining measurements of coronary pressure and flow. The index of microcirculator resistance (IMR), obtained using thermodilution derived mean transit time, has conflicting data whether it is influenced by epicardial stenosis severity. For Doppler flow velocity derived hyperemic microvascular resistance (HMR) this has not been investigated. We aimed to explore whether HMR is a microcirculatory specific value.
Methods: Simultaneous measurements of intracoronary distal Doppler flow velocity and pressure under hyperemic conditions, were obtained in an obstructed and non-obstructed coronary artery in 45 patients. 68 pairs containing one of the 57 obstructed vessels and one of the 55 non-obstructed vessels were formed. HMR was compared between obstructed and non-obstructed vessels using paired samples T-test and the correlation between HMR in the pairs was tested using the Pearson’s test. These analyses were repeated after excluding 3 patients and 7 pairs in which the obstructed vessel had an FFR < 0.60 - which may suggest collateral flow from different territories was present
Results: In the entire cohort, HMR was 2.51±0.88 in obstructed versus 2.40±0.88 mmHg/cm per second in non-obstructed values, was not significantly different (P=0.331). HMR values in the obstructed and non-obstructed vessels were significantly correlated: R=0.491, P<0.001. After exclusion of obstructed vessels with an FFR < 0.60, HMR approached equipoise in obstructed and non-obstructed vessels: 2.41±0.84 vs. 2.40±0.90 mmHg/cm per respectively (P=0.922). The correlation coefficient improved to: R=0.540; P<0.001 after exclusion of vessels with FFR < 0.60.
Conclusions: HMR is a microcirculatory specific value that is independent of the presence of a stenosis, especially in vessels not receiving collateral supply. These results indicate that HMR can indeed be used clinically to assess microcirculatory function regardless of the presence of an epicardial coronary stenosis.
Author Disclosures: G.A. de Waard: None. K.M. Marques: None. S.S. Nijjer: None. P.F. Teunissen: None. P.M. van de Ven: None. J.E. Davies: Ownership Interest; Modest; Patented technology. Consultant/Advisory Board; Modest; Volcano Corporation. P. Knaapen: None. N. van Royen: None.
- © 2015 by American Heart Association, Inc.