Dependence of clinical outcomes on time of hospital admission in patients with ST-segment elevation myocardial infarction.

Background: There are conflicting results in studies investigating the effects of percutaneous coronary intervention (PCI) on the prognosis of patients with ST-segment elevation myocardial infarction (STEMI) during or outside of usual hospital working hours. While some researchers have reported higher mortality rates in STEMI patients admitted outside of working hours, others did not find a statistically significant difference.

Objectives: Investigate the short-term endpoints and long-term outcomes of STEMI patients by time of admission.

Design: Retrospective SETTING: Tertiary percutaneous coronary intervention center.

Patients and methods: Patients were grouped by admission, which consisted of four intervals: 06:00 to <12:00, 12:00 to <18:00, 18:00 to <24:00, and 24:00 to <06:00. We analyzed demographic, clinical and mortality by admission time interval and mortality by multivariate analyses, including the time intervals.

Main outcome measures: Clinical data and mortality SAMPLE SIZE: 735 patients; median (IQR) age 62 (22) years; 215 (29.3%) women.

Results: Patients admitted at night were 1.37 times more likely to experience pulmonary edema than patients whose symptoms started in the daytime (P=.012); 32.9% of the patients whose symptoms started at night presented with Killip class II-IV, while during the daytime, 21.4% presented with Killip class II-IV (P=.001). Among the patients, the most common was inferior STEMI (38.6%). However, no-reflow was significantly higher during the daytime compared to the nighttime (P=.12). The risk of the cardiac arrest on admission was 1.2 times higher in patients admitted at night (P=.034). Neither time interval of admission nor several other variables had an effect on clinical outcome or mortality.

Conclusions: While patients admitted at night presented with pulmonary edema and cardiogenic shock more frequently, no reflow was observed during the day after the procedure. Although patients admitted at night with STEMI presented with worse clinical conditions, similar results were observed between the groups in clinical outcomes.

Limitations: More "real world" results might have been obtained if the study had replicated more typical referral conditions for PCI.

Conflict of interest: None.