Abstract 14647: Influence of Increased Microvascular Resistance on FFR Measurements after Successful PCI
Background: There have been concerns that microvascular dysfunction could limit the maximal and constant microvascular vasodilation, which are the requisites of fractional flow reserve (FFR) measurement. Increased microvascular resistance may impair hyperemic coronary flow, resulting in an underestimation of the translesional pressure gradient with a possible overestimation of FFR. Aim: We assessed the hypothesis that increased microvascular resistance represented by an index of microcirculatory resistance (IMR) may lead to an overestimation of FFR in patients with successful percutaneous coronary intervention (PCI).
Methods: A total of 90 coronary arteries from 90 patients treated with successful stenting (less than 20% residual stenosis with TIMI 3 flow grade) underwent FFR and IMR measurements during maximal hyperemia induced by intravenous administration of 160µg/kg/min of adenosine triphosphate. FFR values were compared among quartiles based on IMR values. The relationship between FFR and IMR was also assessed by linear regression analysis. Hyperemic mean transit time (Tmn) was evaluated for the assessment of coronary flow. Quantitative coronary angiography analysis (QCA) was performed with the use of CMS-MEDIS system.
Results: IMR values were distributed in the wide range from 7.7 to 89.2. Median IMR value was 19.8 and IMR values of each quartile were 10.6 (IQR 9.0 - 12.5), 15.4 (IQR 14.8 - 17.8), 24.0 (IQR 21.9 - 26.1), 40.0 (IQR 34.4 - 45.8), respectively. Median FFR was 0.89 (IQR 0.85 - 0.96). FFR values were significantly greater in the highest quartile of IMR values (p=0.004). FFR showed a significant linear relationship with IMR (r=0.32, p=0.002). Increase in IMR value by 20 overestimated FFR by 0.03. Coronary flow represented by Tmn showed significant reduction in the highest IMR quartile. There was no significant difference in QCA analyses across the IMR quartiles.
Conclusion: IMR values after successful PCI were widely distributed, and increased IMR was not uncommon. Increased IMR values may lead to the overestimation of FFR by the reduction of coronary flow after successful PCI.
- © 2012 by American Heart Association, Inc.