Quantitative Flow Ratio

A less invasive method of pressure guidewire-free image-based fractional flow reserve (FFR) computation has been developed and investigated comprehensively. Quantitative flow ratio (QFR) is one of the image-based FFR computed using three-dimensional quantitative coronary angiography and estimated flow velocity. Several studies, including meta-analyses have reported that QFR had a good diagnostic accuracy compared with wire-based FFR as reference standards, and was rapidly computed for approximately 5 minutes per vessel. Furthermore, the diagnostic performance of QFR to detect myocardial ischemia has been found to be comparable with that of other modalities, such as instantaneous wave-free ratio, myocardial perfusion imaging and FFR derived from computed tomography (FFR-CT).Considering the advantages of QFR compared with wire-based FFR, i.e. (1) less invasive, (2) acceptably accurate, and (3) quickly computed, QFR may be potentially preferred in clinical applications for specific situations, such as risk stratification in multivessel disease, non-culprit lesion assessment in ST-segment elevation myocardial infarction (STEMI), strategic guidance for percutaneous coronary intervention (PCI), and post-PCI lesion assessment.This review article highlights the current usage, clinical implications, and future perspectives of angiography-derived FFR, particularly QFR, one of the primary computations investigated in this field.