Elective Coronary Stenting Increases Fractional Flow Reserve in Other Arteries due to an Increase in Microvascular Resistance: Clinical Implications for Assessment of Multivessel Disease

Abstract

Fractional flow reserve (FFR) can guide percutaneous coronary intervention (PCI) in multivessel disease (MVD). However, the effect of target vessel (TV) stenting on subsequent FFR measurements in remote non-TVs (NTVs) is unknown. We investigated the effect of TV stenting on NTV FFR in patients with MVD. Patients with MVD (>50% stenosis, ≥2 vessels >2.5 mm diameter; n = 51) undergoing elective PCI were studied. NTV distal pressure, aortic pressure, and saline-bolus thermodilution transit time (Tmn) were measured at baseline and during maximal hyperemia to derive FFR, index of myocardial resistance (IMR), and coronary flow reserve (CFR). PCI was then performed to the TV and the measurements repeated. Collaterals were assessed by modified Rentrop score before and after TV stenting. Mean FFR increased in the NTV after stenting the TV (0.79 ± 0.02 vs. 0.81 ± 0.02; P < 0.01), particularly in patients with normal baseline IMR (0.77 ± 0.02 vs. 0.80 ± 0.02; P = 0.001; n = 41). In this group, PCI to the TV increased remote microvascular resistance (NTV IMR increased from 12.5 ± 0.7 to 16.3 ± 1.4; P = 0.007; and CFR decreased from 3.0 ± 0.2 to 2.4 ± 0.2; P = 0.008). This change was independent of angiographic loss of coronary collaterals from the NTV. Elective TV PCI increases NTV FFR due to an increase in remote coronary microvascular resistance in patients with normal microvascular function. The effect of stent deployment on subsequent FFR measurements in other arteries should be considered.