Introduction: Patients with ST-segment elevation myocardial infarction (STEMI) often undergo percutaneous coronary intervention (PCI) procedures during their index hospitalisation. However, some factors may increase the risk of major adverse cardiac event (MACE) outcomes after delaying PCI. We aimed to determine the risk factors for MACE outcomes in acute STEMI patients who had PCI during their index admission. Methods: In this retrospective single-center study, the medical records of STEMI patients who had PCI during their index hospitalisation in our facility were retrieved. At 30 days and six months post-PCI, demographic characteristics, clinical presentation, coronary risk factors, and the rate of MACE outcome were recorded and analysed. Results: This study included 91 STEMI patients. At 30 days and six months post-PCI, the rate of MACE was 10.5% and 8.0% respectively. At 30 days post-PCI, gender (p = 0.025), systolic blood pressure (p = 0.005) and heart rate (p = 0.003) were all associated with MACE outcomes. At six months, systolic blood pressure (p = 0.017), heart rate (p = 0.003), and previous coronary artery disease (CAD) (p = 0.014) were all associated with MACE. Conclusion: In acute STEMI patients, female gender, systolic blood pressure, heart rate, and a history of CAD are the risk factors for MACE outcomes after the PCI during the index admission. However, this is only single center study with short follow up period. Therefore, multi centers study and longer follow up period could provide better understanding on the factors associated with delayed PCI.