Objective: To explore the clinical value of three-dimensional ultrasound speckle tracking imaging (3D-STI) on evaluating the left ventricular myocardial strain and predicting the major adverse cardiac events (MACEs) after percutaneous coronary intervention (PCI) in patients with myocardial infarction (MI). Methods: Totally 105 patients with MI who underwent PCI in the hospital from October 2019 to October 2022 were selected as the research subjects. During hospitalization, the corresponding drugs and PCI therapy recommended by the guidelines were performed on patients. 3D-STI examination was performed to evaluate the cardiac function of patients before discharge, and the patients were routinely followed up for 1 year after discharge and were divided into MACEs group (n=14) and non-MACEs group (n=91) according to the presence or absence of MACEs. The general data, cardiac function indicators and myocardial strain indicators were compared between the two groups. Pearson correlation analysis was used to analyze the relationship between left ventricular myocardial strain indicators and LVEF. ROC curve was applied to analyze the clinical value of left ventricular myocardial strain indicators on predicting MACEs after interventional therapy. Results: There were no statistically significant differences in gender, disease history, history of oral medication and the number of stents between MACEs group and non-MACEs group (P>0.05). The age and target vessel diameter stenosis rate in MACEs group were significantly older or higher than those in non-MACEs group. The LVEF, global area strain (GAS), global circumferential peak strain (GCS), global longitudinal peak strain (GLS) and global radial peak strain (GRS) were significantly lower in MACEs group than those in non-MACEs group. Pearson analysis showed that the myocardial strain indicators were positively correlated with LVEF (P<0.05). ROC analysis revealed that the myocardial strain indicators had high efficiency on predicting the occurrence of MACEs after interventional therapy (P<0.05). Conclusion: The application of 3D-STI can accurately evaluate the left ventricular myocardial strain in patients with MI, and myocardial strain indicators have certain reference value om predicting the occurrence of MACEs after interventional therapy, and it can provide comprehensive guidance for early clinical identification of poor prognosis in patients with MI.