Changes in microvascular resistance following percutaneous coronary intervention - From the ILIAS global registry

Background: Microvascular resistance (MR) has prognostic value in acute and chronic coronary syndromes following percutaneous coronary intervention (PCI), however anatomic and physiologic determinants of the relative changes of MR and its association to target vessel failure (TVF) has not been investigated previously. This study aims to evaluate the association between changes in MR and TVF.Methods: This is a sub-study of the Inclusive Invasive Physiological Assessment in Angina Syndromes (ILIAS) registry which is a global multicentre initiative pooling lesion-level coronary pressure and flow data.Results: Paired pre-post PCI haemodynamic data were available in n = 295 vessels out of n = 828 PCI treated patients and of these paired data on MR was present in n = 155 vessels. Vessels were divided according to increase vs. decrease % in microvascular resistance following PCI (Delta MR % <= 0 vs. Delta MR > 0%). Decreased microvascular resistance Delta MR % <= 0 occurred in vessels with lower pre-PCI fractional flow reserve (0.67 +/- 0.15 vs. 0.72 +/- 0.09 p = 0.051), coronary flow reserve (1.9 +/- 0.8 vs. 2.6 +/- 1.8 p < 0.0001) and higher hyperemic microvascular resistance (2.76 +/- 1.3 vs. 1.62 +/- 0.74 p = 0.001) and index of microvascular resistance (24.4 IQ (13.8) vs. 15. 8 IQ (13.2) p = 0.004). There was no difference in angiographic parameters between Delta MR % <= 0 vs. Delta MR > 0%. In a cox regression model Delta MR % > 0 was associated with increased rate of TVF (hazard ratio 95% CI 3.6 [1.2; 10.3] p = 0.018).Conclusion: Increased MR post-PCI was associated with lesions of less severe hemodynamic influence at baseline and higher rates of TVF at follow-up.