Abstract: Objective:To investigate the correlation between the expression of P-selectin (PS) , platelet-lymphocyte aggregate (PLy A) , and mean platelet volume-lymphocyte ratio (MPVLR) in patients with acute myocardial infarction (AMI) and the myocardial perfusion level after percutaneous coronary intervention (PCI) and their predictive value for PCI outcome.Methods:A total of 180 AMI patients treated with PCI in our hospital between September 2017 and November 2020 were included and divided into the no-reflow group and reflow group according to the level of myocardial perfusion immediately after PCI. The two groups were compared for the baseline data and pre-PCI levels of PS, PLy A, and MPVLR. The myocardial perfusion levels of patients with different expression levels of PS, PLy A and MPVLR were compared. The correlation between each of these indices and the level of myocardial perfusion, as well as the related influencing factors of no-reflow, were analyzed. A nomogram prediction model of no-reflow after PCI was constructed using R language.Results:There were significant differences in Gensini score of coronary artery lesions and use of Tirofiban between the no-reflow group and the reflow group ( P<0.05) . The no-reflow group had higher levels of PS [ (192.56±45.26) ng/L vs (148.19±40.66) ng/L], PLy A [ (13.68±) 4.19) % vs (8.28±2.57) %], and MPVLR [ (8.05±2.26) vs (4.97±1.50) ] compared with the reflow group ( P<0.05) . The myocardial perfusion level significantly differed between patients with higher and lower levels of PS, PLy A, and MPVLR ( P<0.05) . PS, PLy A, and MPVLR were closely associated with TIMI blood flow grades and no reflow ( P<0.05) . The nomogram prediction model of PCI outcome based on the Gensini score of coronary artery disease, Tirofiban use, PS, PLy A, and MPVLR for the risk of no-reflow fitted well with the actual risk of death. Conclusion:In AMI patients, expression of PS, PLy A, and MPVLR is significantly abnormal, closely associated with the level of myocardial perfusion, and therefore may can effectively predict the occurrence of no reflow after PCI.