Association of Prolonged Emergency Department Length of Stay with Adverse Events in Patients with Non-ST-Elevation Acute Coronary Syndrome

Objective: To study the association between prolonged emergency department length of stay (EDLOS) and in-hospital adverse events in patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Methods: In this retrospective cohort study, the medical records of 738 patients diagnosed with NSTE-ACS and admitted to the emergency department (ED) from 1 January 2013 to 31 December 2019 were reviewed. The patients were categorized into groups with EDLOS < 4 hours and EDLOS >= 4 hours, and baseline characteristics, clinical presentation, Killip classification, Global Registry of Acute Coronary Events score, investigations, use of the European Society of Cardiology (ESC) 0/1-hour and 0/3-hour algorithms, and treatments in the ED were compared between the groups. The associations of in-hospital adverse events with EDLOS were examined using univariate logistic regression. Results: Four hundred and twenty-three (57.3%) patients had an EDLOS of >= 4 hours, and the median (IQR) EDLOS was 4.48 hours (3.03, 6.20 hours). EDLOS >= 4 h was associated with a prolonged time to receive P2Y(12) inhibitors and anticoagulants (P < 0.001). However, the two groups showed no significant differences in in-hospital adverse events (congestive heart failure [CHF], shock, stroke or transient ischemic attack [TIA], major bleeding, arrhythmia, recurrent myocardial infarction, death, and one or more adverse events). Nevertheless, a non-significant trend for a higher rate of adverse events (CHF, shock, major bleeding, arrhythmia, recurrent myocardial infarction, death, and one or more adverse events) with longer EDLOS was observed in the subgroup of patients who received diuretic or antiarrhythmic drugs, ventilator or bilevel positive airway pressure support, oxygen support, or inotropic/vasopressor drugs in the ED. Conclusion: Prolonged EDLOS showed a significant association with longer times to receive P2Y(12) inhibitors and anticoagulants. However, the EDLOS < 4 hour and EDLOS >= 4 hour groups of patients with NSTE-ACS showed no significant differences in the rates of in-hospital adverse events. Patients who receive cardiovascular medications in the ED or are on respiratory support should be hospitalized as soon as practically possible. Proper use of the 0/1-hour algorithm over the 0/3-hour algorithm without unnecessary repeated cardiac troponin tests in the ED could reduce the EDLOS in patients with NSTE-ACS.