AIM To explore the relationship between changes of flow-mediated dilation (FMD) before and after percutaneous coronary intervention (PCI) and the plaque vulnerability, as well as its predictive value for prognosis.

METHODS One hundred and six patients who underwent PCI treatment in our hospital from June 2019 to February 2021 were selected as the study subjects. They were divided into vulnerable plaque (VP) group (n=53) and stable plaque (SP) group (n=53) based on the examination results of optical coherence tomography (OCT) and were subsequently matched using propensity scores. The clinical data and changes in FMD values before and after PCI treatment were compared between the two groups. Logistic analysis was made of the relationship between vulnerable plaque subtypes and FMD, independent risk factors affecting coronary plaque vulnerability and the correlation between FMD levels and prognosis after PCI.

RESULTS Compared with the VP group before propensity score matching, the SP group showed significant differences in age, low BMI, long disease course, low alcohol consumption, low proportion of hyperlipidemia, low proportion of coronary heart disease, low proportion of T2DM, low proportion of cerebrovascular disease, and ACS type. Except for hyperlipidemia, P<0.01, all other items were P<0.05. After matching, there was no statistically significant difference in each item between the two groups, and the curve graph tended to be consistent. The matching effect was good, effectively improving the baseline feature balance. Compare the vascular related data of the lesion between two groups of patients on the 7th day after surgery. Compared with the VP group, the SP group had low NC, low FT, and low PL (all P<0.05), high fiber cap thickness, and high FMD (all P<0.01). FMD has the highest correlation with ruptured plaques in vulnerable plaque subtypes, which is 1.99 times that of stable plaques, while concentric plaques have the lowest correlation, which is 1.68 times that of stable plaques. FMD is an independent risk factor affecting the vulnerability of coronary plaques, while FMD, PL, and fiber cap thickness are independent risk factors affecting the prognosis after PCI. There is a stable correlation between FMD levels and postoperative prognosis of PCI in subgroups with different PL, fiber cap thickness, inflammatory response, macrophage infiltration, and cholesterol crystallization levels, and there is interaction between subgroups. CONCLUSION The FMD value after PCI is significantly lower than before PCI and FMD is an independent risk factor that can predict the risk of plaque vulnerability. FMD, PL and fiber cap thickness are independent risk factors that affect the prognosis after PCI and are of important predictive value for the prognosis after PCI.