Comparison of Quantitative Flow Ratio and Invasive Physiology Indices in a Diverse Population at a Tertiary United States Hospital.

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.