FFR VERSUS IFR IN ASSESSMENT OF LESION HEMODYNAMIC SIGNIFICANCE AND EXPLANATION OF THEIR DISCREPANCIES. INTERNATIONAL, MULTICENTER AND PROSPECTIVE TRIAL – THE FIGARO STUDY.

Background
Prospective registry of FFR/iFR discrepancy.
Methods 
FFR/iFR were analyzed using a Verrata wire, and coronary flow reserve (CFR) was analyzed using a Combomap machine (both Philips-Volcano). The risk polymorphisms for endothelial nitric oxide synthase (ENOS), and for hemooxygenase-1 (HO-1) were analyzed.
Results
In total, 1884 FFR/iFR measurements from 1564 patients were included. The FFR/iFR discrepancy occurred in 393 measurements (20.9%): FFRp (positive) / iFRn (negative) type (264 lesions, 14.0%), and FFRn/iFRp (129 lesions, 6.8%) type. CFR was measured in 343 lesions, correlating better with iFR (R=0.56, p<0.0001) than FFR (R=0.36, p<0.0001). The CFR value in FFRp/iFRn lesions (2.24 ± 0.7) was significantly higher compared to both FFRp/iFRp (1.39 ± 0.36), and FFRn/iFRn lesions (1.8 ± 0.64, p<0.0001).
Multivariable logistic regression analysis confirmed: 1/ sex, age, and lesion location in the right coronary artery as predictors for FFRp/iFRn discrepancy; 2/ hemoglobin level, smoking, and renal insufficiency as predictors for FFRn/iFRp discrepancy.
The FFRn/iFRp type of discrepancy was significantly more frequent in patients with both risk type of polymorphisms (ENOSr+HO-1r): 8 patients (24.2%) compared to FFRp/iFRn type of discrepancy: 2 patients (5.9%), p= 0.03.                                                         Conclusions                                                                                                                                                                                     Predictors for FFRp/iFRn discrepancy were sex, age, and location in the right coronary artery. Predictors for FFRn/iFRp were hemoglobin level, smoking, and renal insufficiency. The risk type of polymorphism in ENOS and HO-1 genes was more frequently found in patients with with FFRn/iFRp type of discrepancy.