Objective: It is crucial for patients with acute coronary syndrome (ACS) to receive appropriate coronary intervention in the early stages including prehospital care of the disease, as the severity of reperfusion injuries and the mortality rate increase with the delay in coronary intervention after symptom onset. This retrospective observational study was performed to determine the appropriate mode of arrival through a comparative analysis of the initial triage, treatment timeline, and treatment outcome in a cohort of patients with ACS who underwent coronary angiography.

Methods: The participants of this study were 118 adult patients (≥19 years of age) who were admitted to emergency departments at one regional-level medical center and underwent coronary angiography between January 1, 2016 and December 31, 2017. Among them, 46 patients were admitted by Emergency Medical services (EMS), 48 were walk-in patients, and 24 were transferred from other hospitals. Collected data were analyzed using SPSS 22.0 for Windows (IBM, USA).

Results:
1) Based on the initial assessment at triage, there was a significantly greater proportion of those classified as either KTAS Level 1 or 2 among patients admitted by EMS (91.3%) than among walk-in patients (60.5%). Meanwhile, among patients classified as KTAS Level 3 or 4, the proportion of walk-in patients (39.6%) was significantly greater than that of transferred patients (16.7%) or patients admitted by EMS (8.7%) (p=.006).
2) Blood tests for cardiac biomarkers performed in the emergency center showed that CK-MB levels were significantly higher in the group of transferred patients than in the other two groups (p<.000). For examining treatment timeline, the median values of the following variables were compared among groups: symptom to door time (p<.000); door to triage time (p<.000); and door to ECG time (p<.000). All three variables were lower in the group of patients admitted by EMS than in the other two groups. However, door to coronary angiography time (p=0.003) and door to balloon time (p=0.041) were significantly shorter for the group of transferred patients.
3) Regarding treatment outcomes and prognosis, there was no significant difference in hospitalization period among the three groups (median value, 5 days). Moreover, there was no significant difference in the overall survival after discharge. The rate of the onset of other cardiovascular diseases within one year after discharge was higher in the group of transferred patients (43.5%) than in the group admitted by EMS (20.0%) or the group of walk-in patients (17.8%), but the difference was not significant.

Conclusion: The results of this study showed that ACS patients who used EMS reached the emergency center faster after symptom onset, received initial triage assessment at earlier stages, and underwent important examinations (i.e., the 12-lead ECG) faster. Based on these observations, it appears that there is a need for national public health education to inform patients with cardiovascular symptoms to use EMS. Based on the findings and limitations of this study, we suggest that benefits observed throughout the treatment process support the promotion of paramedic service use after the onset of cardiovascular symptoms, even though treatment outcomes do not differ significantly. Additional studies should be performed in the future with a larger sample size. The characteristics and reasons for the use of modes of arrival other than paramedic services, despite the evident benefits observed throughout the treatment process, should be analyzed.