The association between admission time and in-hospital mortality in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention: A retrospective cohort study

Background: Timely reperfusion is crucial for improving outcomes in ST-segment elevation myocardial infarction, yet the “off-hour effect”, where patients admitted during nights, weekends, or holidays experience delays and potentially worse outcomes remains debated, particularly in resource-limited settings like Vietnam. This study aimed to evaluate the association between admission time and in-hospital mortality among STEMI patients at a 24-hour PPCI capable center in Central Vietnam.

Methods: This study included patients diagnosed with acute STEMI according to the 2023 European Society of Cardiology guidelines and treated with emergency coronary angiography and PPCI at Thanh Hoa General Hospital between April 2023 and December 2024. Admission times were classified as on-hours (7:00 AM - 5:00 PM, Monday - Friday) or off-hours (all other times, including nights, weekends, and public holidays). Data on demographics, clinical characteristics and in-hospital outcomes were collected from medical records and patient interviews. Multivariable analysis was used to adjust for confounders and other risk factors.

Results: The study consisted of 201 patients with 11 in-hospital deaths (5.5%). The proportion of patients under 60 years old was higher in the group of patients admitted during off-hours (p=0.03). No statistically significant differences were found in gender, current residence and medical history across the on-hours groups. Patients admitted during off-hours experienced significantly longer D2B times compared to those admitted during on-hours (260 minutes vs 194 minutes, p=0.02). However, we found no statistically significant difference in in-hospital mortality rates between the on-hours and off-hours groups (p>0.99). Factors such as age, blood pressure, and Killip classification were not independent predictors of mortality in the study.

Conclusions: Despite longer reperfusion delays during off-hours, the in-hospital mortality rates remained comparable. These findings offer exploratory evidence regarding the implementation of current protocols in a middle-resource setting. Larger multicenter studies are needed to confirm these observations and evaluate their applicability across different regions.