Effect of an acute coronary syndrome triage protocol in an emergency department on the door-to-balloon time for patients with ST elevation myocardial infarction.

Abstract

Introduction: Chest pain is a major reason for emergency department (ED) visits and acute hospital admittance. Identifying patients with acute coronary syndrome (ACS) within the large proportion of patients with suspected cardiac chest pain represents a diagnostic challenge for professionals in the ED. Based on assessment of symptoms, history and the 12-lead electrocardiogram (ECG) findings, a patient with ST-elevation myocardial infarction (STEMI) should be identified and treated as soon as possible, since door-to-balloon time is strongly associated with the likelihood of survival. In case of STEMI, primary percutaneous coronary intervention (primary PCI) is indicated, international guidelines recommend a door-to-balloon time in patients with STEMI less than 90 minutes. Within the ED of Medisch Spectrum Twente (MST) the protocol "ACS triage ED" was introduced in January 2010, to shorten door-to-balloon times in patients with STEMI. To identify STEMI, a monitor with computer algorithm interpretation of the 12-lead ECG was used. Aim of this study was to evaluate the effect of the ACS triage protocol, executed by emergency nurses. Methods: A quasi-experimental cohort control group design was used to compare patients with chest pain before and after implementation of the protocol “ACS triage ED”. Primary outcome measure was door-to-balloon time and secondary endpoints included enzymatic infarct size, length of stay in the ED and in hospital, and presence of chest pain, mortality and re-admission at 30-day follow-up. Data were extracted retrospectively from ED, hospital and PCI databases and cardiology medical records. Results: In the after period, 215 consecutive patients were registered in the ED database with chest pain. Seven patients underwent PCI for myocardial infarction (MI), four of them had STEMI. Before implementation, 881 consecutive patients presented to the ED with chest pain, 29 underwent PCI, of which 20 were diagnosed with STEMI. Patient characteristics were comparable between the two total groups, but not between the two subsets of patients with MI who underwent PCI. Median door-to-balloon time for patients with STEMI was longer in the after group (88 minutes before and 120 minutes after; P=0.10), but was shorter for the patients with NSTEMI (1518 minutes before versus 277 minutes after; P=0.78). None of the STEMI patients in the after group was treated within 90 minutes after arrival at the ED. Peak CK level was higher in the after group (1071 ng/ml before versus 1458 ng/ml after; P=0.59), length of stay in the ED was prolonged (from 31 minutes before to 49 minutes after; P=0.42), as well as length of stay in the hospital (from 5 days before to 6 days after; P=0.50). Clinical outcomes at 30-day follow up did not differ between before and after group. Conclusions: In the after group a longer median door-to-balloon time was registered in patients with STEMI undergoing a primary PCI after admission through the ED of MST. Time of arrival during off-hours and hemodynamic instability at arrival were identified as possible reasons for delay in these patients. Clinical outcomes appear to be worse in the after group, but may have been caused by the poorer health status at arrival of these patients. For patients with NSTEMI, the median door-to-balloon time appeared to be shorter in the after group, despite increases in the median length of stay in the ED.