Functional assessment of coronary stenosis: an overview of available techniques. Is quantitative flow ratio a step to the future?

Introduction: The assessment of coronary lesions severity has always been a relevant topic in the management of the patient undergoing coronary angiography. Fractional flow reserve (FFR) has been introduced as an objective index to determine the significance of a coronary stenosis with a positive impact on clinical outcomes has been demonstrated for FFR-guided coronary interventions. However, several technical drawbacks have been pointed out in clinical practice limiting the diffusion of FFR worldwide. To exceed these limits, other indices and the quantitative flow ratio (QFR) have been recently developed and tested in clinical studies. Areas covered: This review aims to provide a brief overview of functional assessment of coronary stenosis and a particular attention to the QFR, to its validation and application studies for its potential applicability in clinical practice. QFR through a computational fluid dynamic analysis, proved to be useful in discriminating functionally significant stenosis, with an excellent correlation with FFR values, and considerable advantages in terms of acquisition time and costs. Expert opinion/commentary: QFR is an innovative angiographic-based technique that uses modern software for three-dimensional vessel reconstruction, and flow models calculation. The significant technical benefits reported in the management of patients with intermediate coronary stenosis, make it a modern, effective and usable tool.