Angiography-Derived Fractional Flow Reserve in the SYNTAX II Trial: Feasibility, Diagnostic Performance of Quantitative Flow Ratio, and Clinical Prognostic Value of Functional SYNTAX Score Derived From Quantitative Flow Ratio in Patients With 3-Vessel Disease

Abstract

ObjectivesThe aims of the present study were to investigate the applicability of quantitative flow ratio (QFR) in patients with 3-vessel disease and to demonstrate the impact of functional SYNTAX (Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery) score derived from QFR (fSSQFR) on clinical outcomes. BackgroundThe applicability of QFR in patients with 3-vessel disease and the feasibility of fSSQFR have not yet been investigated. MethodsAll lesions interrogated using instantaneous wave-free ratio and/or fractional flow reserve in the SYNTAX II trial were retrospectively screened and analyzed for QFR. The diagnostic performance of QFR was investigated using hybrid wire-derived pressure assessment (instantaneous wave-free ratio and fractional flow reserve), used in the trial as a reference. Patients with analyzable QFR in 3 vessels were stratified according to fSSQFR to evaluate its clinical prognostic value on the basis of 2-year patient-oriented composite endpoint. ResultsQFRs were analyzable in 71.0% of lesions (836 lesions). The diagnostic performance of QFR to predict binary wire-based ischemia was substantial (area under the curve 0.81, accuracy 73.8%), with a positive predictive value of 85.9%. Independent predictors of diagnostic discordance were lesions in side branches, involvement of bifurcation or trifurcation, and small vessel. According to the 2-year patient-oriented composite endpoint, fSSQFR reclassified 26.1% of the patients (36 of 138) in the high- to intermediate-risk group into the low-risk group appropriately (net reclassification improvement 0.32; p < 0.001). The area under the curve for fSSQFR to predict the 2-year patient-oriented composite endpoint was higher than that of the classic anatomic SYNTAX score (0.68 vs. 0.56; p = 0.002). ConclusionsQFR demonstrated substantial applicability in patients with 3-vessel disease. The fSSQFR has the potential to further refine prognostic risk estimation compared with the classic anatomic SYNTAX score.