Factors Influencing In-Hospital and Long-Term Mortality in Patients with Acute ST-Elevation Myocardial Infarction Undergoing Primary Percutaneous Intervention

Objective: To identify factors associated with in-hospital and long-term mortality among patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI) in a regional hospital in Thailand. Materials and Methods: This retrospective cohort study analyzed patients with STEMI who received primary PCI from January 2014 to December 2022. Demographic characteristics, clinical presentation, angiographic findings, procedural details, and clinical outcomes were extracted from medical records. The primary outcome was long-term all-cause mortality during a 3-year follow-up period. Survival probabilities were estimated using the Kaplan-Meier method, and Cox proportional hazards regression assessed factors associated with long-term mortality. Statistically significant defined as p<0.05. Results: The 283 patients with STEMI undergoing primary PCI were analyzed, with 12 (4.2%) dying during hospitalization. Long-term survival data included 270 patients. 3-year and 5-year survival rates were 81.0% and 78.4%, respectively. Non-survivors were older and presented with greater clinical severity. Kaplan-Meier analysis showed significantly lower survival among patients with Killip class III-IV and those who achieved a myocardial blush grade (MBG) ≤2 after PCI (log-rank p<0.001). Multivariable Cox regression, age >65 years, left ventricular dysfunction, mechanical ventilation, chronic obstructive pulmonary disease, a greater number of stents, and severe coronary calcification on angiography were independently associated with increased long-term mortality. In contrast, achievement of MBG 3 (adjusted HR 0.28, 95% CI 0.13-0.64, p=0.002), longer duration of dual antiplatelet therapy (adjusted HR 0.07, 95% CI 0.02-0.28, p<0.001), and eGFR 60-89 mL/minute/1.73 m² (adjusted HR 0.24, 95% CI 0.09-0.65, p=0.005) were independently associated with lower long-term mortality. Conclusion: Long-term mortality remained substantial. Older age and greater clinical severity were associated with poorer outcomes, whereas achievement of MBG 3 was associated with improved long-term survival, highlighting the importance of early risk stratification and optimized reperfusion strategies