Impact of morphofunctional assessment with quantitative flow ratio and optical coherence tomography in patients with acute coronary syndromes.

Background: Combining morphological and physiological evaluations might improve the risk stratification of patients who undergo percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) culprit lesions.
Aims: We aimed to investigate the clinical utility of morphofunctional evaluation after PCI for identifying ACS patients with increased risk of subsequent clinical events.
Methods: We retrospectively studied 298 consecutive ACS patients who had undergone optical coherence tomography (OCT)-guided PCI. We performed OCT-based morphological analysis and quantitative flow ratio (QFR)-based physiological assessment immediately after PCI. The non-culprit segment (NCS) was defined as the most stenotic untreated segment in the culprit vessel. The primary outcome was target vessel failure (TVF), a composite of cardiac death, target vessel-related myocardial infarction, and ischaemia-driven target vessel revascularisation.
Results: During a median follow-up period of 990 days, 42 patients experienced TVF. Cox regression analysis revealed that the presence of thin-cap fibroatheroma (TCFA) in the NCS and a low post-PCI QFR, or the presence of TCFA in the NCS and a high ΔQFR in the NCS (QFR _NCS ), were independently associated with TVF. The subgroup with TCFA in the NCS and a low post-PCI QFR had a significantly higher incidence of TVF (75%) than the other subgroups, and those with TCFA in the NCS and a high ΔQFR _NCS had a significantly higher incidence of TVF (86%) than the other subgroups. The integration of TCFA in NCS, post-PCI QFR, and ΔQFR _NCS with traditional risk factors significantly enhanced the identification of subsequent TVF cases.
Conclusions: Combining post-PCI OCT and QFR evaluation may enhance risk stratification for ACS patients after successful PCI, particularly in predicting subsequent TVF.