Among patients with acute coronary syndrome (ACS), optical coherence tomography (OCT)-derived fractional flow reserve (FFR) is associated with target vessel failure (TVF) after percutaneous coronary intervention (PCI) at a median follow-up of 36 months, and the presence of both OCT-FFR and thin-cap fibroatheroma (TCFA) in a non-culprit vessel makes TVF more than 8 times likely than in other vessels, new study results show.