Background:~Patients at high risk of having one or more coronary stenosis are evaluated routinely by invasive coronary angiography (CAG). Lesions are often quantified by QCA, but fractional flow reserve is increasingly used to assess functional significance of identified stenosis. FFR is assessed during CAG by advancing a wire with a pressure transducer towards the stenosis and measure the ratio in pressure between the two sides of the stenosis during medical induced maximum blood flow (hyperaemia).~The solid evidence for FFR evaluation of coronary stenosis and the relative simplicity in performing the measurements have supported adoption of an FFR based strategy in many centers but the need for interrogating the stenosis by a pressure wire, the cost of the wire, and the drug inducing hyperaemia limits more widespread adoption.~Quantitative Flow Ratio is a novel method for evaluating the functional significance of coronary stenosis by calculation of the pressure drop in the vessel based on two angiographic projections.~The FAVOR I study (Tu et al.), showed promising results for core laboratory QFR analysis in selected patients.~The purpose of the FAVOR II study is to evaluate the feasibility and diagnostic precision of in-procedure QFR during CAG in comparison to QCA with FFR as gold standard for physiological lesion evaluation.~Hypothesis: QFR has superior sensitivity and specificity for detection of functional significant lesions in comparison to QCA with FFR as gold standard~Methods: Prospective, observational, multicenter study with inclusion of 310 patients.~Patients with indication for FFR are enrolled. At least two angiographic projections are acquired during resting conditions. QFR is calculated in-procedure using the Medis Suite application and simultaneously to the operator performing the FFR measurement. The QFR observer is blinded to the FFR measurement.~QFR is reassessed off-line by the Interventional Coronary Imaging Core Laboratory, Aarhus University, Denmark, blinded to FFR and in-procedure QFR results.~FFR is assessed by core laboratory reading, blinded to QFR results. All data are entered and stored in a protected and logged trial management system (TrialPartner, Aarhus University, Denmark).
Quantitative Flow Ratio (QFR) is a novel method for evaluating the functional significance of coronary stenosis. QFR is assessed by calculation of the pressure in the vessel based on two angiographic projections. The purpose of the FAVOR II study is to evaluate the diagnostic accuracy of on-line QFR compared to 2D Quantitative Coronary Angiography (QCA) with FFR as gold standard.