Prognostic Role of Functional SYNTAX Score Based on Quantitative Flow Ratio

Background/Objectives: The quantitative flow ratio (QFR)-based functional Synergy Between Percutaneous Coronary Intervention with Taxus and Cardiac Surgery (SYNTAX) score (FSSQFR) combines coronary arteries’ anatomy and physiology. Methods: We performed an offline FSSQFR calculation in all-comers undergoing coronary angiography in a single center. Based on the tertiles of SYNTAX Score (SS), patients were divided into low-, intermediate-, and high-risk groups with the following cut-offs: SS/FSSQFR < 13, SS/FSSQFR: 13–21, and SS/FSSQFR: >21. The primary endpoint was the predictive value of the FSSQFR of the composite endpoint of all-cause death, myocardial infarction, ischemia-driven revascularization, hospitalization for heart failure, and life-threatening arrhythmias after the follow-up period. Results: This study included 410 patients. SS and FSSQFR were measured for all patients. After calculating FSSQFR, the risk stratification changed in 11% of the study population; more specifically, 26.8, 32.7, and 40.5% of patients were classified as high-, intermediate-, and low-risk, respectively. After a median 30.2 (25.7–33.7) months follow-up period, we recorded 85 events of the primary outcome. The high-risk FSSQFR group compared to the low-risk group had a significantly higher rate of the primary composite outcome (HR: 1.95, 95% CI 1.33–3.34, p = 0.016). Conclusions: In our study, patients classified as the high-risk FSSQFR group had a significantly higher rate of cardiovascular adverse events.