Quantitative flow ratio—Meta‐analysis and systematic review

Abstract

Introduction Despite of the wide evidence of use fractional flow reserve (FFR), isolated angiography evaluation is still the main tool to indicate percutaneous coronary intervention. Quantitative flow ratio (QFR) is a new functional index to assess functional significance. Recently, few studies have showed the capacity of QFR to predict significance stenosis. The aim of this research has been to describe the evidence of QFR in this clinical setting, to analyze the global diagnosis accuracy of QFR versus FFR and to compare the difference in feasibility between retrospective and prospective analysis. Methods and results Systematic review of literature was performed. Eligible studies for the meta‐analysis were considered those directly evaluating de QFR versus FFR. Pooled values of diagnosis test and summary receiver operator curve were calculated. Main causes of not‐perform QFR analysis according to study design were also evaluated. Sixteen studies were included. Good correlation and agreement were showed. Global sensibility, specificity, PPV, and NPV were 0.84, 0.89, 0.80, and 0.92, respectively. Then, 18% of evaluated vessels could not be analyzed. Significant differences were found in the percentage of discarded vessels and the cause of nonperformed analysis between retrospective or prospective analysis. Conclusions Excellent correlation and agreement between QFR and FFR was demonstrated. QFR assessment could be improved by its prospective analysis with a dedicated protocol.

Ten‐year clinical outcomes in patients with intermediate coronary stenosis according to the combined culprit lesion

“…However, these technologies may not be available in all cardiac laboratories. In addition, the clinical application of functional study has been variable and remains underused 13,14 …”

“…Moreover, functional stenosis severity of non‐culprit lesions is frequently overestimated 12 . And the utilization of FFR is increasing, however, the many cardiac laboratories still making clinical decision based on coronary angiography alone due to the equipment availability, reimbursement policies, and other financial considerations 13,14 …”

Quantitative Flow Ratio

“…In a meta-analysis of 13 studies using angiography-derived FFR with various methodologies for 1,842 vessels, pooled sensitivity, specificity, and summary area under the receiver-operating curve (ROC) against FFR (cut-off value of 0.8) were 89%, 90%, and 0.84, respectively 21) . In another meta-analysis of 16 studies including 3,335 vessels for a direct comparison between QFR and FFR, the correlation coefficient, sensitivity, specificity, and area under the ROC were 0.82, 84%, 89%, and 0.94, respectively 22) .…”

“…Coronary lesions or vessels lacking two optimal angiographic projections (at least 25° apart), such as overlapping interrogated vessels, an absence of preferred references in proximal or distal vessels (i.e., ostial lesion), and excessive foreshortening on the angiogram, are inappropriate for QCA/QFR analysis, and thereby excluded from major validation studies. Therefore, the QFR feasibility was relatively high in prospectively-enrolled cohorts with optimised angiogram acquisition protocols 17,20,22,25) . Second, coronary microcirculatory dysfunction may negatively affect the accurate evaluation of QFR, explaining any discrepancies between QFR and wire-based FFR.…”

Performance of Integrated Near-Infrared Spectroscopy and Intravascular Ultrasound (NIRS-IVUS) System against Quantitative Flow Ratio (QFR)

“…QFR applies fluid dynamics equations and is calculated from three-dimensional quantitative coronary angiography (3D-QCA). It was previously validated and showed high diagnostic accuracy in identifying hemodynamically significant stenosis and the prediction of ≤0.8 FFR [ 4 , 5 , 6 ].…”