QFR Versus FFR Derived From Computed Tomography for Functional Assessment of Coronary Artery Stenosis

The aim of this study was to compare diagnostic performance between quantitative flow ratio (QFR) derived from coronary angiography and fractional flow reserve derived from computed tomography (FFR_CT) using fractional flow reserve (FFR) as the reference standard.

QFR and FFR_CT are recently developed, less invasive techniques for functional assessment of coronary artery disease.

QFR, FFR_CT, and FFR were measured in 152 patients (233 vessels) with stable coronary artery disease.

QFR was highly correlated with FFR (r = 0.78; p < 0.001), whereas FFR_CT was moderately correlated with FFR (r = 0.63; p < 0.001). Both QFR and FFR_CT showed moderately good agreement with FFR, presenting small values of mean difference but large values of root mean squared deviation (FFR-QFR, 0.02 ± 0.09; FFR-FFR_CT, 0.03 ± 0.11). The sensitivity, specificity, positive predictive value, and negative predictive value of QFR ≤0.80 for predicting FFR ≤0.80 were 90%, 82%, 81%, and 90%, respectively. Those of FFR_CT ≤0.80 for predicting FFR ≤0.80 were 82%, 70%, 70%, and 82%, respectively. The diagnostic accuracy of QFR ≤0.80 for predicting FFR ≤0.80 was 85% (95% confidence interval [CI]: 81% to 89%), whereas that of FFR_CT ≤0.80 for predicting FFR ≤0.80 was 76% (95% CI: 70% to 80%).

QFR and FFR_CT showed significant correlation with FFR. Mismatches between QFR and FFR and between FFR_CT and FFR were frequent.