The Impact of Mode of Presentation to the ED on Time Metrics for STEMI Patients

A look at whether the door-to-balloon time of patients with ST elevation myocardial infarction (STEMI) varied based upon mode of arrival to the ED.

Abstract

OBJECTIVE: To investigate whether the door-to-balloon (D2B) time of patients with ST elevation myocardial infarction (STEMI) varied based upon mode of arrival to the emergency department and to determine if mode of arrival in these patients was related to preferred spoken language.

METHODS: Authors analyzed a series of 100 STEMI cases evaluated in the emergency department of a major urban teaching hospital as to mode of arrival to the emergency department (ED) and preferred spoken language.

RESULTS: A substantial increase in electrocardiogram (ECG) acquisition time and time to percutaneous coronary intervention (PCI) laboratory activation was found for STEMI patients presenting by private vehicle (PV). Also, a significant increase was found in the likelihood of arrival by private vehicle for Spanish-speaking STEMI patients as compared to English-speaking STEMI patients.

CONCLUSIONS: Arrival to the emergency department by private vehicle was associated with an increase in the time to acquisition of ECGs and time to activation of the PCI laboratory in patients with STEMI. Also, factors such as language barriers influence decisions in mode of transport to the hospital in these patients.

List of Abbreviations

ALS: Advanced Life Support

D2B: Door to balloon

ECG: Electrocardiogram

ED: Emergency department

EMS: Emergency medical services

PCI: Percutaneous coronary intervention

PV: Private vehicle

STEMI: ST Elevation myocardial infarction

Introduction

STEMI is a life-threatening condition requiring prompt evaluation and management to prevent irreversible damage to the heart muscle or death.

Systems of care have evolved allowing emergency medical services (EMS) professionals to identify STEMI in the prehospital arena and provide rapid activation of the percutaneous coronary intervention (PCI) laboratories at the destination facilities.

Alternatively, the STEMI patient presenting by PV to the emergency department must be identified by medical staff members to allow PCI laboratory activation.

The authors sought to determine whether EMS vs. PV presentation for STEMI patients affected the various components of D2B time in their emergency department. The authors further sought to determine if a relationship existed between preferred spoken language and mode of presentation to the hospital.

Methods

This study analyzed patient medical records of 100 random STEMI cases which resulted in emergent PCI laboratory activation who presented to Parkland Hospital Emergency Department (ED) in Dallas, TX, between 2014 and 2019.

Each record included mode of arrival, preferred spoken language, the initial 12-lead ECG, pre- and post- catheterization laboratory images, and computed times from arrival to the emergency department until balloon inflation in the PCI laboratory. The time intervals included:

  1. Arrival in ED to ECG order placed;
  2. ECG order to ECG acquisition;
  3. ECG acquisition to activation of the PCI laboratory;
  4. Activation to departure to the PCI laboratory;
  5. Departure from ED to arrival at the PCI laboratory;
  6. PCI laboratory arrival to stick;
  7. Stick to balloon;
  8. Total time in ED;
  9. Total door-to-balloon time.

The authors also wished to determine if an association existed between mode of arrival to the emergency department and preferred spoken language. The STEMI patients were categorized into their preferred language of choice: English, Spanish, and other.

These data were entered into Excel and analyzed by mode of arrival to generate comparisons and statistical analysis of both groups. Box and whisker plots were created for both patient types to identify any trends. Data points with negative time intervals were determined to be data entry errors and were excluded from the analysis.

Results

Of the 100 STEMI patients studied, 66 patients (66%) arrived at the hospital by PV while 34 (34%) arrived by EMS. The analysis of the box and whisker plots revealed that on average, patients arriving by EMS required 4.1 minutes from hospital arrival to electrocardiogram (ECG) acquisition, 4.1 minutes from ECG acquisition to activation of the PCI laboratory, and 26.4 minutes total time in the ED from arrival until departing for PCI (“total ED time”), resulting in a 63.4-minute mean D2B time (see Figure 1).

Patients who arrived by PV averaged 2.4 minutes from arrival to ECG acquisition, 19.5 minutes from ECG to PCI activation, 42.7 minutes in the ED, with a mean D2B time of 73.8 minutes.

The 10.4-minute difference in the two D2B times equated to a 16.4% longer D2B time for patients who arrived by PV (see Figure 2).

The data regarding preferred spoken language versus mode of arrival revealed that 25 English speaking STEMI patients arrived by EMS while 33 arrived by PV. On the other hand, 6 Spanish speaking STEMI patients arrived by EMS while 36 arrived by PV.

Thus, English speaking STEMI patients were 32% more likely to arrive by PV, but Spanish speaking STEMI patients were 600% more likely to arrive by PV.

Figure 1

Figure 1 displays the time it took for patients presenting via emergency medical services (EMS) to complete various protocol phases. Blue represents arrival to electrocardiogram (ECG), orange represents ECG to percutaneous coronary intervention (PCI) activation, and grey from the emergency department (ED) to the PCI laboratory. The total time in yellow represents door to balloon (D2B) mean time for patients presenting by EMS.

Figure 2

Figure 2 displays the time it took for patients presenting via private vehicle (PV) to complete various protocol phases. Orange represents arrival to electrocardiogram (ECG), grey represents ECG to percutaneous coronary intervention (PCI) activation, and yellow from the emergency department (ED) to the PCI laboratory. The total time in blue represents door to balloon (D2B) mean time for patients presenting by PV.

Limitations

This study of ED STEMI patients who received PCI did not extend to patient outcome following intervention but rather only examined ED processes in the management of these patients. Thus, the impact on patient outcome due to the identified increase in ECG acquisition to PCI activation time in patients presenting by PV was not assessed. Future study could be conducted to ascertain whether this additional time has a meaningful effect on patient outcome.

Discussion

STEMI patients present management challenges to hospital emergency departments and staff members. This review demonstrated that for 100 STEMI patients who presented to a large urban teaching hospital by either EMS transport or PV, there was a 10.4 minute (16.4%) increase in D2B time for those patients arriving by PV.

Increasing door to balloon time has been shown to be associated with a heightened mortality risk in STEMI patients. Evidence has demonstrated that patients with a D2B time ≤90 minutes had the lowest in-hospital mortality rate (3%), followed by 4.2% at 91-120 minutes, 5.7% at 121-150 minutes, and >150 minutes at 7.4%.1

The present study found that patients with STEMI presenting by PV sustained an almost five-fold increase in ECG acquisition to activation time (4.1 vs. 19.5 minutes), which could be associated with a higher risk of mortality.

This study found that patients with STEMI presenting by PV sustained an almost five-fold increase in ECG acquisition to activation time (4.1 vs. 19.5 minutes), which could be associated with a higher risk of mortality.

In addition, patients presenting by PV incur increased risks while en route to the hospital. These hazards include the absence of the attention of a trained medical professional and cardiac monitoring, the lack of treatment prior to arrival with appropriate medications (including aspirin, oxygen as indicated, and pain control), and the risk of cardiac arrest en route.

Also, patients transported by PV do not have the ability to have a 12 lead ECG acquired prior to arrival which could be transmitted in anticipation of earlier PCI laboratory activation. The absence of these benefits prior to arrival plus the risk of cardiac arrest while enroute may increase both morbidity and mortality.

As discussed, patients who are transported by EMS typically receive evaluation en route, including a 12-lead ECG which may be transmitted to the receiving facility allowing for expedited PCI laboratory activation, reducing D2B time for the patient. One study revealed that 95% of patients who had earlier activation met the standard of a D2B time ≤60 minutes, while the standard activation group only met the goal 64% of the time.2 Thus, not only may EMS transport reduce D2B times overall for STEMI patients due to ED processes, but for those cases in which PCI is activated while the EMS transport is en route to the hospital, the time interval may be reduced even more.

Patients arriving by PV to our facility experienced an average 15.4-minute delay from ECG acquisition to PCI laboratory activation when compared to EMS patients (4.1 minutes to 19.5 minutes).

Patients arriving by PV to our facility experienced an average 15.4-minute delay from ECG acquisition to PCI laboratory activation when compared to EMS patients (4.1 minutes to 19.5 minutes).

A previously published study from our facility in 2008 focused on minimizing the overall D2B time, including the ECG acquisition to activation interval, through a multi-procedural process.

The authors of that study reported a decrease in ECG acquisition time to PCI laboratory activation from 40 minutes to 11 minutes for all STEMI patients.3

As a whole, the present study found similar ECG to activation time for all patients at 12.8 minutes.

However, this study – stratified by mode of patient arrival – found an almost five-fold increase in this interval when the patient arrived by PV rather than via EMS.

During this study at our facility, for a STEMI patient presenting by PV, the following steps occurred during patient management:

  1. The Triage staff member performed the 12-lead ECG,
  2. Located an emergency physician to interpret the ECG, usually by walking to another location within the emergency department
  3. The emergency physician interpreted the ECG, initiated an evaluation of the patient, and proceeded with PCI laboratory activation if indicated.

Thus, both geographical and process issues contributed to the significant increase in the departmental delay for patients arriving by PV. The authors propose that as it is now customary for paramedics staffing advanced life support (ALS) ambulances to interpret 12-lead ECGs, perhaps a similar effort might be undertaken in the training of Triage personnel in emergency departments, perhaps allowing earlier activation of the PCI laboratory by staff in the patient intake or Triage area.

Our study suggests the need for emergency receiving facilities to continuously monitor the processes involved in the management of STEMI patients and that these processes may vary according to mode of presentation of the patients.

For example, when a patient is inbound via EMS with a STEMI patient, pre-arrival processes can be mobilized that limit D2B time through early PCI laboratory activation. Similar efforts should be made for STEMI patients arriving by PV through non-EMS patient intake areas.

The study also found another interesting dichotomy when the mode of transportation to the hospital and preferred spoken language was analyzed. In our series, 25 English speakers and 6 Spanish speakers were transported by EMS, while 33 English speakers and 36 Spanish speakers were transported via private vehicle (PV).

Thus, 32% more English speakers arrived by PV than by EMS, whereas 600% more Spanish speakers arrived by PV than by EMS, a concerning finding in these critically ill STEMI patients.

These data present an urgent need to increase community outreach to help enhance patient safety during mobilization to hospital facilities in the hope of optimizing patient outcomes. The need for a larger study of this matter is evidenced through these data.

32% more English speakers arrived by PV than by EMS, whereas 600% more Spanish speakers arrived by PV than by EMS

Conclusion

In this study of a large urban medical center, a relationship was found between mode of arrival and D2B time for STEMI patients who received PCI. Transportation by PV increased D2B time principally due to the additional time required from ECG acquisition until PCI lab activation. Emergency departments at hospitals with PCI capability must adopt procedures for optimizing the time from ECG acquisition until PCI laboratory activation in patients with STEMI presenting by PV.  

In addition, further investigation regarding the reasons why some patients present by PV rather than utilizing EMS is warranted, with careful attention to the matter of cultural diversity.

References

1.         McNamara RL, Wang Y, Herrin J, et al. Effect of door-to-balloon time on mortality in patients with ST-segment elevation myocardial infarction. J Am Coll Cardiol. 2006;47(11):2180-2186. doi:10.1016/j.jacc.2005.12.072

2.         Stowens JC, Sonnad SS, Rosenbaum RA. Using EMS Dispatch to Trigger STEMI Alerts Decreases Door-to-Balloon Times. West J Emerg Med. 2015;16(3):472-480. doi:10.5811/westjem.2015.4.24248

3.         Parikh SV, Treichler DB, DePaola S, et al. Systems-based improvement in door-to-balloon times at a large urban teaching hospital: a follow-up study from Parkland Health and Hospital System. Circ Cardiovasc Qual Outcomes. 2009 Mar;2(2):116-122. DOI: 10.1161/circoutcomes.108.820134.

4.   Tate RC. The Need for More Prehospital Research on Language Barriers: A Narrative Review. West J Emerg Med. 2015;16(7):1094-1105. doi:10.5811/westjem.2015.8.27621

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