Diagnostic Performance of Angiography-Derived Quantitative Flow Ratio: A Systematic Review and Meta-Analysis

Background: Quantitative flow ratio (QFR) is a novel technology to assess the functional significance of coronary stenoses based on standard coronary angiography, which can be alternatives to invasive fractional flow reserve (FFR) assessment. However, the evidence is limited to single-center studies and small sample sizes. This study systematically determined the diagnostic performance of QFR to diagnose functionally significant stenosis with FFR as the reference standard. Methods: A systematic review and meta-analysis of studies assessing the diagnostic performance of angiography-derived QFR systems were performed. All relevant studies from six literature databases were searched and screened according to the inclusion and exclusion criteria. The pooled sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR), along with their 95% confidence intervals (CIs), were calculated using DerSimonian-Laird methodology. The summary receiver operating characteristic (SROC) curve and area under the curve were estimated. Meta-regression analysis was performed to identify a potential source of heterogeneity. Results: Fifty-seven studies comprising 13,215 patients and 16,125 vessels were included in the final analysis. At the vessel level, the pooled sensitivity and specificity of QFR for detecting a significant coronary stenosis were 0.826 (95% CI: 0.798-0.851) and 0.919 (95% CI: 0.902-0.933). Pooled LR+ and LR- were 10.198 (95% CI: 8.469-12.281) and 0.189 (95% CI: 0.163-0.219), with a pooled DOR of 53.968 (95% CI: 42.888-67.910). The SROC revealed an area under the curve (AUC) of 0.94 (95% CI: 0.91-0.96). The summary AUCs were 0.90 (95% CI: 0.87-0.92) for fixed-flow QFR (fQFR), 0.95 (95% CI: 0.92-0.96) for contrast-flow QFR (cQFR), 0.97 (95% CI: 0.95-0.98) for Murray law-based QFR (μQFR), and 0.91 (95% CI: 0.89-0.94) for non-specified QFR. The adjusted pooled DORs were as follows: 126.25 for μQFR, 45.49 for cQFR, 26.12 for adenosine-flow QFR (aQFR), 25.88 for fQFR, and 36.54 for non-specified QFR. Conclusions: The accuracy of angiography-derived QFR was strong to assess the functional significance of coronary stenoses with FFR as a reference. μQFR demonstrated the highest diagnostic performance among the five evaluated modes.