SummaryIt is unknown whether there has been any change in the causes of death for acute ST-segment elevation myocardial infarction (STEMI) in the era of aggressive reperfusion. We analyzed the direct causes of in-hospital death in patients with STEMI treated with primary percutaneous coronary intervention (PCI) in a tertiary referral center over the past 10 years.We retrospectively analyzed 878 STEMI patients treated with primary PCI in our hospital between January 2005 and December 2014. There were no significant changes in the age and sex of patients, but the prevalence of hypertension and smoking decreased. STEMI severity increased with more patients in Killip classification > 2. The number of out-ofhospital cardiac arrest events also increased over the 10 years. Symptom onset-to-door time did not change in the 10-year study period. The care quality was improved with shorter door-to-balloon time for primary PCI and increased use of dual antiplatelet therapy. The all-cause in-hospital mortality was 9.1%, which did not vary over the 10 years. Multivariable analysis showed that Killip classification > 2 was the most important determinant of death. Cardiogenic shock was the major cause of cardiovascular death. There was an increase in non-cardiovascular causes of death in the most recent 3 years, with infection being a major problem.Despite improvement in care quality for STEMI, the in-hospital mortality did not decrease in this tertiary referral center over these 10 years due to increased disease severity and non-cardiovascular causes of death. (Int Heart J 2016; 57: 541-546) Key words: Acute myocardial infarction, Coronary angioplasty, Mortality A cute myocardial infarction is an important public health issue in Taiwan because it carries a high fatality rate and its incidence is still increasing. 1) In acute ST-segment elevation myocardial infarction (STEMI), timely primary percutaneous coronary intervention (PCI) and the use of evidence-based medications significantly decrease mortality, and are strongly recommended in local 2) and international guidelines.3,4) In Taiwan, more than 95% of STEMI patients received primary PCI as the initial reperfusion therapy, and the door-to-balloon (D2B) time has improved. 5,6) A previous observational study demonstrated that early primary PCI could decrease the incidence of cardiogenic shock, which is the major cause of death in STEMI.7) It is unknown whether there has been any temporal change in the causes of death during hospitalization for STEMI with the advent of aggressive reperfusion in recent years. Information on the specific causes of death can reveal the weak points of current treatment and enable the implementation of new strategies to improve the quality of care for STEMI patients treated with primary PCI. The major aims of the present study were to describe the 10-year secular trends in the clinical characteristics and management of STEMI patients treated with primary PCI, and to specifically analyze the causes of death in these patients in a tertiary referral c...