Prognostic significance of emergency department bypass in stable and unstable patients with ST-segment elevation myocardial infarction

Abstract

Background: In ST-segment elevation myocardial infarction (STEMI) patients treated with percutaneous coronary intervention, direct transport from the scene to the catheterisation laboratory bypassing the emergency department has been shown to shorten times to reperfusion. The aim of this study was to investigate the effects of emergency department bypass on mortality in both haemodynamically stable and unstable STEMI patients. Methods: The analysis is based on a large cohort of STEMI patients prospectively included in the German multicentre Feedback Intervention and Treatment Times in ST-Elevation Myocardial Infarction (FITT-STEMI) trial. Results: Out of 13,219 STEMI patients who were brought directly from the scene by emergency medical service transportation and were treated with percutaneous coronary intervention, the majority were transported directly to the catheterisation laboratory bypassing the emergency department ( n=6740, 51% with emergency department bypass). These patients had a significantly lower in-hospital mortality than their counterparts with no emergency department bypass (6.2% vs. 10.0%, P<0.0001). The reduced mortality related to emergency department bypass was observed in both stable ( n=11,594, 2.8% vs. 3.8%, P=0.0024) and unstable patients presenting with cardiogenic shock ( n=1625, 36.3% vs. 46.2%, P<0.0001). Regression models adjusted for the Thrombolysis In Myocardial Infarction (TIMI) risk score consistently confirmed a significant and independent predictive effect of emergency department bypass on survival in the total study population (odds ratio 0.64, 95% confidence interval 0.56–0.74, P<0.0001) and in the subgroup of shock patients (OR 0.69, 95% CI 0.54–0.88, P=0.0028). Conclusion: In STEMI patients, emergency department bypass is associated with a significant reduction in mortality, which is most pronounced in patients presenting with cardiogenic shock. Our data encourage treatment protocols for emergency department bypass to improve the survival of both haemodynamically stable patients and, in particular, unstable patients. Clinical Trial Registration: NCT00794001 ClinicalTrials.gov: NCT00794001