Mode of arrival does not predict myocardial infarction in patients who present to the ED with chest pain

Aims: This study aims to determine if patients who arrive by ambulance with a chief complaint of chest pain have a higher risk of myocardial infarction (MI) than those who arrive via alternate transportation.

Methods: All patients ages 18-99 who presented to an urban academic ED between January 2006 and July 2006 with a chief complaint that included "chest pain" were eligible for retrospective analysis. Patients who were transferred or who left without being seen or against medical advice were excluded. Myocardial infarction was defined as patients who were admitted and who had elevated troponin I or went urgently to catheterization laboratory and had >90% occlusion of a vessel, with a final clinical impression of MI.

Results: There were 690 visits for chest pain during the study period, representing 4% of total ED census. A total of 39 visits met exclusion criteria, and 37 patients had 52 repeat visits, leaving 599 unique patients included for analysis. Mean age was 48.8 +/- 1.4 years (SD 17.7), 44.6% were female, and 35 patients (5.8%) were diagnosed with MI. In all, 157 patients (26.2%) arrived via EMS. Patients who arrived by ambulance did not have a significant difference in rate of MI when compared with alternate transportation [7.0% vs. 5.4%, OR (95% CI) = 1.3 (0.6-2.7), p = 0.469]. Only 31.4% (11/35) of patients who ultimately were diagnosed with MI arrived by ambulance.

Conclusion: We were unable to show a significant difference in rate of MI between patients who arrived via ambulance or private transportation. Equal consideration and urgency should be given to both types of patients when they arrive at the ED.