Background

Circadian variability is prevalent in ST-segment elevation myocardial infarction (STEMI), such that the highest incidences occur in the morning hours. There is conflicting evidence on whether the time of day of presentation with STEMI is associated with differences in short-term outcomes. We therefore sought to evaluate the impact of admission time on survival in patients presenting with STEMI. 

Methods

892 consecutive patients admitted with STEMI, who received primary percutaneous coronary intervention at a high-volume tertiary hospital between September 2016 and September 2022, were retrospectively analyzed. Statistical analyses were based on data from a data warehouse utilizing the hospital information system including ICD and OPS codes as well as biometric data and biomarker values on individual patient levels. The primary endpoint was in-hospital mortality, secondary endpoints were the length of stay, left ventricular ejection fraction, acute kidney injury, and biomarker levels. 

Results

Of the 892 patients, 19% (172) were female, the mean age was 61 years. 23% of patients (204) suffered from cardiogenic shock, 29% (256) were mechanically ventilated. Acute kidney injury (AKI) was diagnosed in 16% (141). The median peak high-sensitive troponin I was 11,716 ng/l [lower quartile 1,028 ng/l, upper quartile 48,504ng/l]. The overall in-hospital mortality was 15% (131).  The lowest mortality was observed in patients presenting with STEMI at 9:00 (13.0%), whereas patients admitted at 17:00 showed the highest mortality (16.1%). There was a symmetric decrease and increase in mortality rates in the 8 hours before and after 9:00 (between 01:00 and 17:00). Regarding AKI, the lowest incidence (12.1%) was detected at 1:00 and 2:00, the highest incidence (18.2%) was observed at 16:00 and 17:00. 

Conclusion

In our study, significant associations were observed between the time of day of admission and mortality in patients presenting with STEMI. Furthermore, AKI was found to be more prevalent at corresponding time intervals. While conclusions are to be regarded as hypothesis-generating, these findings might be explained by adverse presentation at the initial presentation.