Clinical
Use of emergency medical services expedites in-hospital care processes in patients presenting with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention

https://doi.org/10.1016/j.carrev.2014.03.011Get rights and content

Abstract

To determine whether door-to-balloon (DTB) times of patients presenting with ST-elevation myocardial infarction (STEMI) were reduced in patients transported by emergency medical services (EMS) compared to those who were self-transported. DTB time is an important measure of hospital care processes in STEMI. Use of EMS may expedite in-hospital processing and reduce DTB times. A total of 309 consecutive STEMI patients who underwent primary percutaneous coronary intervention in our institution were analyzed. Excluded were patients who received fibrinolytics, presented in cardiac arrest, were intubated, or were transferred from another hospital. EMS-transported patients (n = 83) were compared to self-transported patients (n = 226). The primary outcome measure was DTB time and its component time intervals. Secondary end points included symptom-to-door and symptom-to-balloon times, and correlates for DTB > 90 minutes. A higher percentage of EMS-transported patients reached the time goal of DTB < 90 minutes compared to self-transported patients (83.1 versus 54.3%; p < 0.001). EMS-transported patients had shorter DTB times [median (IQR) minutes, 65 (50–86) versus 85 (61–126); p < 0.001] due to a reduction of emergency department processing (door-to-call) time, whereas catheterization laboratory processing (call-to-balloon) times were similar in both groups. EMS-transported patients had shorter symptom-to-door [median (IQR) hours, 1.2 (0.8–3.5) versus 2.3 (1.2–7.5); p < 0.001] and symptom-to-balloon [median (IQR) hours, 2.5 (1.9–4.7) versus 4.3 (2.6–9.1); p < 0.001]. Independent correlates of DTB times > 90 minutes were self-transport (odds ratio 5.32, 95% CI 2.65–10.70; p < 0.001) and off-hours presentation (odds ratio 2.89, 95% CI 1.60–5.22; p < 0.001). Use of EMS transport in STEMI patients significantly shortens time to reperfusion, primarily by expediting emergency department processes. Community education efforts should focus not only on the importance of recognizing symptoms of myocardial infarction, but also taking early action by calling the EMS.

Introduction

Rapid reperfusion with percutaneous coronary intervention (PCI) is the gold standard therapy for patients presenting with ST-segment elevation myocardial infarction (STEMI) when promptly available [1]. Delays in door-to-balloon (DTB) times correlate with increased morbidity and mortality [2], [3]. Achieving a DTB time of < 90 minutes has become a quality measure of the hospital system performance dealing with STEMI care [1], [4]. With the identification of key strategies to enhance hospital system performances [5], [6], several programs have been successfully implemented to help meet the DTB < 90-minute time goals with timely access to primary PCI [7], [8], [9].

To address the continuum of care for STEMI patients from the onset of symptoms to arrival at the emergency department (ED), the use of emergency medical services (EMS) may potentially facilitate rapid transport, early assessment and treatment, and expedited communication of information with the accepting ED. However, EMS has been shown to be underutilized [10], [11], and a significant proportion of STEMI patients still arrive at the ED via their own transportation.

MedStar Washington Hospital Center (Washington, DC) is a primary PCI facility with around-the-clock cardiac catheterization capabilities catering to Washington, DC, a highly urbanized area with EMS coverage provided fully by the DC Fire and EMS. In addition, it serves as a referring PCI center for other facilities in DC, as well as parts of Maryland and Virginia. MedStar Washington Hospital Center is located in the heart of Washington, DC, and with DC Fire and EMS as the single EMS provider for Washington, DC, this offers us a unique opportunity to analyze modes of transport for STEMI patients within DC, and its impact on pre- and in-hospital care processes leading to reperfusion. Specifically, we aimed to determine if the use of EMS transport may actually reduce overall DTB times by reducing certain components of in-hospital processing times.

Section snippets

Patient population

This retrospective analysis included all patients from January 2007 to December 2012 who presented to the MedStar Washington Hospital Center ED with a STEMI and subsequently underwent primary PCI. Patients who were transferred from a referring institution, patients who suffered cardiac arrest, patients who were intubated, and patients who were given fibrinolytic therapy before the PCI were excluded. The patients were categorized into whether they were self-transported (“self”) or transported by

Results

A total of 309 consecutive STEMI patients who underwent primary PCI were analyzed, of which 226 arrived by self-transport, and 83 were transported by EMS. The baseline and procedural characteristics in both groups were similar. (Table 1, Table 2). The majority of patients from both groups presented to the ED during off hours. A significantly higher percentage of EMS-transported patients achieved the time goals of DTB < 90 minutes and DTB < 120 minutes compared to self-transported patients. (Fig. 2)

Discussion

With continued emphasis on shortening the symptom-to-treatment time in patients presenting with acute myocardial infarction, the present study detects important findings that may impact this mission: 1) compared to self-transport, EMS transport leads to faster in-hospital ED processing time, translating to reduction in DTB time in STEMI patients undergoing primary PCI; 2) EMS-transported patients experienced shorter delays to hospital care from symptom onset; and 3) self-transport and off hours

Conclusion

The use of EMS transport in STEMI patients significantly shortens time to reperfusion by primary PCI, mainly by expediting emergency department processes. Robust EMS programs should be supported with community education outreach efforts that focus not only on the importance of recognizing symptoms of myocardial infarction, but also on taking early decisive action by calling EMS.

References (33)

Cited by (13)

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    The second factor negatively affecting the times is a lasting high percentage of patients who are transported via secondary route, which is again a patient-affected choice. According to our other results, these patient's choices therefore play a key role in determining the total ischaemic time of the patient [5,11]. As illustrated on Fig. 1, patients opting for secondary route in general also take longer to notify the system of the chest pain.

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