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

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.

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.

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).

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.