Objective To investigate the association between the proportion of peripheral blood intermediate monocyte subset (Mon2) and prognosis in patients with acute myocardial infarction (AMI) receiving percutaneous coronary intervention (PCI).

Methods A total of 100 AMI patients who underwent PCI between March 2021 and June 2022 were enrolled. Peripheral venous blood samples were collected within 24 hours of onset in all patients, and monocyte subsets were analyzed using three-color flow cytometry. Patients were followed up for at least 1 year after discharge, and major adverse cardiovascular events (MACE) were recorded.

Results The optimal cut-off point for predicting MACE occurrence 1 year after PCI in AMI patients based on the Mon2 proportion was 25.65% (area under the curve=0.758, 95% CI, 0.607 to 0.909, P=0.002), with a sensitivity of 64.3% and a specificity of 86.0%. Patients were divided into high Mon2 proportion group and low Mon2 proportion group according to the optimal cut-off value. There were significant differences in globulin, creatinine, fasting blood glucose, left ventricular end-systolic diameter, and Mon2 proportion between the two groups (P < 0.05). After adjusting for potential confounding factors using Cox regression, Mon2 proportion was found to be an important indicator for predicting poor prognosis after AMI. Kaplan-Meier survival analysis showed that the Mon2 proportion had a significant impact on the incidence of MACE in AMI patients with different risk stratifications.

Conclusion Mon2 can improve the accuracy of predicting MACE after PCI, providing a new perspective for prognostic assessment in AMI patients. It is helpful for guiding clinical treatment decisions and improving patient prognosis.