Author + information
The instantaneous wave-free ratio (iFR) is a newly developed coronary artery pressure index measured in the wave-free period of diastole in absence of hyperemia. An iFR-guided revascularization strategy was shown to be noninferior to fractional flow reserve (FFR)-guided revascularization strategy in recent randomized controlled trials. The purpose of this study is to evaluate the discrepancies between iFR and FFR and differences in FFR for the intermediate range iFR lesions.
We retrospectively reviewed 1024 intermediate coronary lesions requiring functional evaluation using iFR between January 2015 and June 2016. The intermediate iFR range lesions between 0.86 to 0.93 were included in our analysis. The threshold cutoff value of 0.89 or less for iFR and 0.80 or less for FFR were used to indicate the presence of hemodynamically important stenosis. Discrepancy within the intermediate range iFR lesion was defined as discordant result of iFR cutoff and FFR cutoff.
Among 1024 intermediate coronary lesions, hybrid protocol of measuring FFR was done in 451 coronary lesions, including 351 lesions with intermediate iFR range between 0.86 and 0.93. Of those 351 lesions, 95 lesions (27.1%) had positive FFR and 256 lesions (72.9%) had negative FFR. Of the 351 intermediate iFR range lesions, 92 lesions (26.2%) had discrepancy while 259 lesions (73.8%) were concordant with the FFR result. Of the 92 lesions with discrepancy, 53 lesions (57.6%) had positive iFR while FFR was negative while 39 lesions (42.4%) had negative iFR while FFR was positive. Differences of FFR value for positive iFR with negative FFR was 0.05 (mean 0.85) while the mean value for FFR difference for negative iFR with positive FFR was -0.03 (mean 0.77). Both groups had predominantly LAD lesions (88.7% vs 79.5%, p=0.25). Multivariate analysis did not show any independent predictor for the discrepancy between iFR and FFR.
In this single center, real world retrospective study, majority of the intermediate iFR range lesions had concordant iFR and FFR result while discrepancy was observed in about a quarter of the lesions. Multivariate analysis did not show independent predictors for the discrepancy between iFR and FFR.
IMAGING: FFR and Physiologic Lesion Assessment