Background

Quantitative flow ratio (QFR) is a technology to evaluate the coronary stenosis significance on 3-dimensional quantitative coronary angiography. The aim of this study is to evaluate and compare the QFR versus fractional flow reserve (FFR) and/or instantaneous free-wave ratio (iFR) in a US population with a fair African American population representation.

Methods and results

This was a retrospective, observational and single-center study that enrolled 100 patients who underwent coronary angiography. The diagnostic performance of QFR in terms of sensitivity was 0.80 (95%CI 0.64–0.97) and specificity was 0.95 (95% CI 0.90–1.00), the positive predictive value (PPV) was 0.83 (0.68–0.98), while the negative predictive value (NPV) was 0.94 (0.88–0.99). The overall accuracy was 0.91 and area under the curve (AUC) was 0.92 (95% CI 0.87–0.97).

The R-squared was 0.54 and the Bland-Altman plot showed a bias of 0.0016 (SD 0.063) and limits of agreement (LOA): Upper LOA 0.13 and Lower LOA −0.12. In African Americans (n = 33), accuracy, AUC, sensitivity, specificity (94%; 0.90 [0.80–1.00]; 0.90 [0.71–1.00]; 0.96 [0.87–1.00], respectively) were better than those for the overall population.

Conclusions

In a US-based representative population, vessel QFR accuracy and agreement with FFR as reference is high. Diagnostic performance of QFR in African Americans is also excellent.