Prognostic value of baseline QFR in single-vessel intermediate coronary stenosis

Background and objectives The prognostic value of baseline Quantitative Flow Ratio (QFR) in real-world patients remains unclear. This study aimed to evaluate the prognostic value of baseline QFR and its three-tier model—low, grey-zone, and high QFR—in patients with single-vessel intermediate stenosis. Methods This retrospective study included 478 patients with QFR between 0.70 and 0.90 who underwent coronary angiography between May and June 2023. Patients were stratified into Low (0.70–0.74), Grey-Zone (0.75–0.85), and High (0.86–0.90) QFR groups. The primary endpoint was major adverse cardiac events (MACE); the key secondary endpoint was target vessel failure (TVF). Kaplan–Meier and Cox proportional hazards models were used to evaluate outcomes. Results During the 18-month follow-up period, MACE incidence was 13.5%, 6.6%, and 3.4% in Low, Grey-Zone, and High QFR groups, respectively ( P = 0.008), mainly driven by MI (3.2% vs. 1.4% vs. 0.0%, P = 0.029) and ischemia-driven revascularization (11.5% vs. 6.1% vs. 2.3%, P = 0.004), including ID-TVR (6.7% vs. 3.3% vs. 1.1%, P = 0.027). Each 0.01 increase in QFR was associated with a 7.23% lower risk of MACE ( P = 0.012) and a 10.04% lower risk of ID-TVR ( P = 0.011). Multivariate analysis confirmed QFR group as an independent predictor, with a per-category decrease from High to Low QFR associated with an 86% higher risk of MACE (adjusted HR = 1.858, 95% CI 1.038–3.326, P = 0.037) and a 2.33-fold higher risk of ID-TVR (adjusted HR = 2.333, 95% CI 1.004–5.510, P = 0.049). Conclusions Baseline QFR and its three-tier stratification across the grey-zone and adjacent ranges show a continuous association with adverse events in single-vessel intermediate coronary stenosis, supporting its role in functional evaluation, risk stratification, and prognostic prediction.