[Is FFR_CT a game changer in coronary CT angiography?]

Coronary computed tomography angiography (CCTA) is already of great importance for the primary diagnostic testing for coronary artery disease (CAD) due to its high negative predictive value (NPV) and high sensitivity but, however, limited specificity. The specificity of invasive coronary angiography (ICA) could be increased by integrating the fractional flow reserve (FFR) into the invasive workflow with proof of the hemodynamic relevance of a morphologically detected coronary stenosis. New noninvasive methods of FFR calculations in CT based on computational fluid dynamics (CFD) or machine learning (ML) demonstrate very encouraging results; however, the widespread use of FFR_CT is mainly determined by the image quality and the resulting capabilities of coronary artery segmentation, which could be insufficient in up to 7-12% of CCTAs to calculate FFR_CT, although a morphological assessment is still possible in most cases. Furthermore, FFR_CT cannot be used in total coronary artery occlusion, e.g. to assess the amount of collateral flow. Therefore, FFR_CT calculation alone is not the game changer in diagnosing chronic coronary syndrome (CCS), but the additional use of FFR_CT together with CCTA can be beneficial in ambiguous cases. Additionally, only one commercially available FFR_CT solution exists on the market with an off-site solution, which limits its acute benefits. Several on-site FFR_CT solutions for scientific evaluation exist but can so far only be used for scientific purposes and are not available for clinical use; however, the calculation of FFR_CT from CCTA data is certainly a meaningful supplement to the purely morphological assessment of the coronary arteries. The value of CCTA for the primary diagnosis of CCS in a clinical scenario will be improved when on-site FFR_CT solutions become commercially available.