Sejr-Hansen M, et al. - In patients with ST-segment elevation myocardial infarction (STEMI) with quantitative flow ratio (QFR), fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR), researchers assessed the diagnostic performance of QFR assessment of nonculprit lesions (NCLs) based on acute setting angiograms with the staged setting as reference. In this post-hoc analysis of the iSTEMI study, the iSTEMI study provided staged iFR and FFR data for 146 NCLs in 112 patients. Acute QFR showed a very good diagnostic performance with staged QFR as reference, a good diagnostic performance with staged FFR as reference, and a moderate diagnostic performance with staged iFR as reference.