Quantitative flow ratio and fractional flow reserve mismatch - clinical and biochemical predictors of measurement discrepancy.

Introduction: Fractional flow reserve (FFR) is the gold standard for functional assessment of intermediate lesions. However, assessing a stenosis with pressure wire prolongs the procedure, increases costs and carries a risk of procedure-related adverse events. Quantitative flow ratio (QFR) is a wire-free method for detection of significant ischemia based on 3D reconstruction of angiographic images and TIMI frame count.

Aim: To evaluate the influence of laboratory and clinical variables on QFR-FFR mismatch.

Material And Methods: We retrospectively computed QFR (Medis Suite XA/QAngio XA 3D/QFR, Medis/Netherlands) in suitable cases with corresponding FFR (PressureWire, Abbott, US). Uni-/multivariate analysis was performed to identify clinical and biochemical predictors of QFR-FFR mismatch.

Results: Two hundred six lesions (196 patients, 76% male, mean age: 66.4 ±10.1 years) were included. Chronic kidney disease (CKD) and insulin-treated diabetes mellitus (ITDM) were associated with significantly larger differences between QFR and FFR values (-0.062 ±0.031 vs. -0.025 ±0.068; = 0.027 and -0.059 ±0.07 vs. -0.027 ±0.074; = 0.039; respectively). CKD was associated with a decrease of diagnostic efficiency (AUC = 0.67, 95% CI: 0.46-0.88 vs. AUC = 0.89, 95% CI: 0.84-0.94, = 0.05). For biochemical variables only weak Spearman correlations were identified for hemoglobin concentration ( = -0.18) and hematocrit levels ( = -0.18).

Conclusions: CKD may impair the QFR diagnostic accuracy. Larger, prospective studies are needed to further explore this potential relationship.