FFR=1.0 flow changes after percutaneous coronary intervention

•Percutaneous coronary intervention (PCI) does not necessarily increase coronary flow despite fractional flow reserve (FFR) improvement.•The novel term of anticipated maximum flow (AMF) was introduced as FFR = 1.0 flow.•AMF values of the vessel were significantly different before and after PCI.•AMF impacted the discordance between FFR and the coronary flow improvement.•AMF incrementally predicts coronary flow increase >50% in addition to FFR. The present study investigated the relationships between physiological indices and increased coronary flow during percutaneous coronary intervention (PCI) using a novel index of “anticipated maximum flow” [AMF; theoretical coronary flow of fractional flow reserve (FFR) = 1]. FFR-guided PCI aims to increase coronary flow, whereas recent studies have reported that PCI does not necessarily increase coronary flow despite improvement in FFR. This retrospective analysis was performed in 71 functionally significant lesions treated with elective PCI. AMF obtained by hyperemic average peak coronary flow velocity (h-APV) divided by FFR would not change after PCI given the constant microvascular resistance, which is the assumption of FFR as a surrogate of coronary flow. We evaluated the relationship between AMF and coronary flow during PCI. Post-PCI AMF was significantly different from pre-PCI AMF (p = 0.022), which impacted discordance between FFR improvement and change in coronary flow. Coronary flow increase >50% was associated with smaller minimum lumen diameter (p = 0.010), greater diameter stenosis (p = 0.003), lower pre-PCI FFR (p < 0.001), lower pre-PCI coronary flow reserve (p = 0.001), higher pre-PCI hyperemic stenosis resistance (p < 0.001), lower pre-PCI h-APV (p = 0.001), and lower pre-PCI AMF (p = 0.031). Pre-PCI AMF provided significant incremental predictive capability for coronary flow increase >50% when added to the clinical model including pre-PCI FFR. Pre-PCI AMF provided incremental ability to predict increased coronary flow after PCI and impacted the discordance between FFR improvement and increased coronary flow.