Aims: Quantitative flow ratio (QFR) has been introduced as an angiography-based modality for fast functional coronary lesion assessment and validated against FFR. This study sought to define the prognostic role of pancoronary QFR assessment in patients with acute coronary syndrome (ACS), including post percutaneous coronary intervention (PCI) culprit and non-culprit vessel QFR.

Methods and results: In a total of 792 patients with ACS (48.6% ST segment elevation-ACS and 51.4% non-ST segment elevation-ACS), QFR analyses of post-PCI culprit (n=792 vessels) and non-culprit vessels (n=1231 vessels) were post-hoc performed by investigators blinded to clinical outcomes. Major adverse cardiovascular events (MACE), including all-cause mortality, non-fatal myocardial infarction, and ischemia-driven coronary revascularization within two years after the index ACS event, occurred in 99 patients (12.5%). Quantitative flow ratio with an optimal cut-off value of 0.89 for post-PCI culprit vessels and 0.85 for non-culprit vessels emerged as strongest independent predictor for MACE after ACS (non-culprit artery QFR: adjusted OR 3.78, 95% CI 2.21-6.45, p<0.001; and post-PCI culprit artery QFR: adjusted OR 3.60, 95% CI 2.09-6.20, p<0.001).

Conclusions: The present study for the first time demonstrates the prognostic value of a pancoronary angiography-based functional lesion assessment in patients with ACS. Hence, QFR offers a novel tool for advanced risk stratification and personalized therapeutic management in patients with ACS.