P6173Plaque characteristics on coronary CT angiography in case of discordance between fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR)

Abstract

Abstract Background The usefulness of fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) evaluation has been confirmed in the determination of revascularization of coronary artery disease. When FFR≤0.8 and iFR≤0.89 were regarded as the criteria for positivity, the discordance was noted in approximately 20%, but this cause has not been well established. Purpose The purpose of this study was to investigate the patient background and features on coronary CT angiography (CCTA) showing the discordance between FFR≤0.8 and iFR≤0.89. Methods The subjects were consecutive 85 cases with 108 vessels in which stenosis of 30–90% was detected at one vessel of at least 2mm or more in the major epicardial vessels and FFR and iFR was performed within subsequent 90 days, among suspected cases of coronary arterial diseases which underwent CCTA. The factors showing the discordance between FFR and iFR (patient background, coronary artery calcification score, high risk plaque features on CCTA (positive remodeling, low attenuation plaque), plaque characteristics by a plaque analysis software using a new algorithm called labeling method (vessel volume, plaque volume, lumen volume, plaque length, maximum plaque burden, necrotic core area, fibrous area and calcium area) were evaluated using logistic regression analysis on per-patient and per-vessel basis. Results There were no significant both FFR and iFR positive definite factors on per-patient basis. The lumen volume/vessel volume (OR: 0.93, 95% CI: 0.88–0.98, P=0.0032) (OR: 0.90, 95% CI: 0.85–0.95, P<0.0001),minimum lumen area (MLA) (OR: 0.59, 95% CI: 0.41–0.85, P=0.0006) (OR: 0.64, 95% CI: 0.44–0.92, P=0.0047), the plaque volume/vessel volume (OR: 1.05, 95% CI: 1.01–1.10, P=0.0114) (OR: 1.09, 95% CI: 1.04–1.15, P=0.0002) and maximum plaque burden (OR: 1.08, 95% CI: 1.01–1.15, P=0.0095) (OR: 1.06, 95% CI: 1.00–1.13, P=0.0406) were significant both FFR and iFR positive definite factors on per-vessels basis. Discordance between FFR≤0.8 and iFR≤0.89 was observed in 23 vessels (21.3%) of 19 patients. In FFR positive and iFR negative group (15 vessels, 13.9%), positive remodeling (PR) (OR: 4.38, 95% CI: 1.13–17.00, P=0.0294) was only significant predictor. In FFR negative and iFR positive group, there was no significant predictors. Conclusions In both FFR and iFR, only lumen volume /vessel volume, MLA, plaque volume/vessel volume and plaque burden were significant positive definite factors. As for the discordance between FFR and iFR, PR is significant predictor in FFR positive and iFR negative group.