Validation of a Novel Coronary Angiography-Derived Quantitative Functional Assessment Compared with Wire-Based FFR and IMR: The Prospective Multicenter FAIR Study.

Synchronous computation of coronary angiography-derived fractional flow reserve (CAG-FFR) and coronary angiography-derived index of microcirculatory resistance (CAG-IMR) is a novel coronary angiography-based method for on-site assessment of suspected myocardial ischemia in patients with coronary artery disease (CAD). This trial is a prospective, multicenter, controlled study designed to assess the diagnostic performance of CAG-FFR and CAG-IMR in patients with suspected myocardial ischemia using wire-based FFR and IMR as reference standards. The functional parameters were calculated using a reduced order computational fluid dynamics solver that incorporates thrombolysis in myocardial infarction (TIMI) frame count and aortic pressure recorded by a disposable invasive pressure sensor. CAG-FFR was computed in 325 patients, demonstrating a patient-level diagnostic accuracy of 95.4%, sensitivity of 95.9%, and specificity of 95.1%. The area under the receiver operating characteristic curve (AUC) of CAG-FFR was 0.977. Patient-specific aortic pressure adoption significantly improved the accuracy of CAG-FFR in the "gray zone" compared to fixed-pressure models. In addition, CAG-IMR was successfully computed in 180 patients, showing a patient-level diagnostic accuracy of 95.5%, sensitivity of 96.4%, and specificity of 95.2%. The AUC of CAG-IMR in diagnosing abnormal coronary microcirculatory dysfunction was 0.973. Synchronous computation of CAG-FFR and CAG-IMR demonstrated higher feasibility and excellent diagnostic accuracy compared to wire-based FFR and IMR, highlighting its clinical potential for CAD evaluation.