Diagnostic Accuracy of Quantitative Flow Ratio (QFR) Compared to Instantaneous Flow Wave Free Ratio (iFR) and DILEMMA Score to Predict Fractional Flow Reserve (FFR)

Abstract

Background: Quantitative flow ratio (QFR) is a novel 3D quantitative coronary angiography and computational fluid dynamics technique to calculate fractional flow reserve (FFR). The DILEMMA score is a recent angiographic technique that has incremental predictive value over diameter stenosis to predict FFR. Unlike FFR, instantaneous wave-free ratio (iFR), diastolic pressure ratio (dPR), QFR and DILEMMA score do not require a pressure-wire or hyperaemia induction. Purpose: To compare the diagnostic accuracy of QFR compared to iFR, dPR and DILEMMA score to predict FFR. Methods: Patients who underwent invasive coronary angiography and FFR assessments were retrospectively studied. iFR and dPR were derived from FFR pressure tracings using a proprietary technique. QFR was computed using a commercially available software. Results: 85 lesions (33% FFR significant) were included. Mean FFR was 0.86 ± 0.09. QFR (rs = 0.801; p < 0.001), iFR (rs = 0.710; p < 0.001), dPR25-75 (rs = 0.715; p < 0.001) and DILEMMA score (H test statistic = 40.56, p < 0.001) were strongly correlated with FFR. QFR <0.8 had a sensitivity, specificity, PPV and NPV of 84%, 92%, 76% and 95% respectively of predicting significant FFR (<0.001). On comparison of AUC, QFR (0.94) is a better predictor of FFR compared to iFR (0.88), DPR (0.88) and DILEMMA score (0.9), p < 0.001. Conclusion: QFR is a better predictor of FFR compared to iFR, DPR and DILEMMA score. Further studies are required to confirm its diagnostic accuracy as well as its cost effectiveness for routine clinical practice.