Comparison of Flow Ratio Derived From Intravascular Ultrasound With Coronary Angiography in Stable Coronary Artery Disease: Correlation With Fractional Flow Reserve

Coronary artery disease (CAD) remains a prevalent global health concern, necessitating precise diagnostic strategies for optimal patient management. Fractional Flow Reserve (FFR), defined as the distal-to-proximal pressure ratio across a coronary stenosis during maximal hyperemia and typically measured by a pressure guidewire during coronary angiography (CAG), is considered a gold standard tool for detecting ischemia-causing stenosis and guiding revascularization decisions. However, wire-based FFR has been significantly underutilized due to practical reasons, including its invasive nature and the requirement for hyperemia. Consequently, there is growing interest in developing and validating computational FFR from anatomical information derived from CAG and intravascular imaging modalities, such as intravascular ultrasound (IVUS).

Quantitative flow reserve (QFR), derived from CAG, has been extensively investigated and has demonstrated high diagnostic performance for detecting hemodynamically significant lesions. Beyond CAG, research has indicated that IVUS imaging can also be utilized for computing FFR. IVUS, a widely accepted and powerful modality for evaluating vessel luminal size and characterizing plaque morphology in the context of coronary intervention, has given rise to IVUS-based FFR, known as ultrasonic flow ratio (UFR). UFR has been recently developed, integrating an estimation of physiology with intravascular imaging in the same IVUS pullback. Despite the proven effectiveness of both UFR and QFR, there is currently no evidence supporting the superiority of one technique over the other. In the present study, investigators aim to compare the diagnostic performance of UFR and QFR for the detection of functionally significant coronary lesions, using conventional FFR as the gold standard.