Bypassing Emergency Department Reduces Reperfusion Time in Primary PCI

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Bypassing emergency department evaluation and directly transporting patients with ST-segment elevation myocardial infarction (STEMI) diagnosed by field ECG to a cath lab shortens time to reperfusion, according to a registry study published online June 20, 2013, in Circulation. The authors suggest the practice, widely adopted in Europe, deserves further exploration and advocacy in the United States.

The 2012 European Society of Cardiology STEMI guidelines recommend that STEMI patients diagnosed with a prehospital ECG bypass ED evaluation. However, this recommendation was not endorsed by the recently updated 2013 American College of Cardiology Foundation/American Heart Association STEMI guidelines.

To evaluate the contemporary practice of bypassing the ED  in the United States, Matthew T. Roe, MD, MHS, of the Duke Clinical Research Institute (Durham, NC), and colleagues examined data from 12,581 patients treated at 371 PCI-capable hospitals participating in the ACTION Registry–Get With The Guidelines–Mission: Lifeline program from July 1, 2008, to March 31, 2011. All patients had a prehospital ECG diagnosis of STEMI with bypass of the ED occurring in 1,316 (10.5%).

Bypass Inconsistent, Infrequent

During the study period, bypassing the ED increased from 8.5% to 11.5%. While the proportion of the overall STEMI population transported by EMS remained unchanged at approximately 50%, the use of prehospital ECGs performed by EMS increased from 47% to 55%.

There was substantial variability across hospitals in the practice of bypassing the ED, ranging from 0% to 71.0% (median, 3.3%). Presentation during working hours was strongly associated with higher likelihood of bypassing the ED (OR 7.58; 95% CI 6.47-8.89; P < 0.0001).

The time from first medical contact to hospital arrival was longer with ED bypass compared with ED evaluation, but the median first medical contact to guidewire introduction, or ‘device activation time,’ was shorter and was more frequently achieved within 90 minutes (table 1).

Table 1. Reperfusion Time Intervals

P < 0.0001 for all.

Compared with those who underwent ED evaluation, more patients who bypassed the ED achieved first medical contact-to-device times within 90 minutes both during working hours (84.2% vs. 68.9%) and during off-hours (69.0% vs. 43.5%; both P < 0.0001). Among ED-evaluated patients, the median time in the ED was greater during off-hours than working hours (36 vs. 22 minutes).

The adjusted in-hospital mortality rate was similar between the 2 groups (adjusted OR 0.69; 95% CI 0.45-1.03; P = 0.07) and remained so after exclusion of patients with heart failure and/or shock on presentation, and those with documented nonsystem reasons for delay (adjusted OR 0.66; 95% CI 0.33-1.31; P = 0.24).

Why No Mortality Benefit?

In an editorial accompanying the study, Elliott M. Antman, MD, of Brigham and Women’s Hospital (Boston, MA), chair of the writing committee for a previous version of the ACC/AHA STEMI Guideline, ponders how to reconcile the fact that bypassing the ED was associated with a lower system delay yet did not translate into improved in-hospital outcomes.

One explanation, he notes, may be that the lack of a mortality benefit from bypassing the ED was simply due to “too small an impact of system delay (30 minutes) and too short a follow-up period (in hospital outcomes).” Other considerations such as less complicated STEMI presentations in ED bypass patients and exclusion criteria also may confound the ability to detect such a signal, he writes.

However, Dr. Antman stresses that “[u]ltimately we need to see a reduction in total ischemic time, which involves recognition of STEMI symptoms by patients.”

In a telephone interview with TCTMD, Patrick T. O’Gara, MD, of Brigham and Women’s Hospital (Boston, MA), chairman of the writing committee for the 2013 ACCF/AHA STEMI guidelines, agreed with Dr. Antman, noting that the data are a welcome addition that were not available when the writing committee finished its document last year. He added that he does not find the ESC and ACCF/AHA STEMI guidelines to be discordant.

“Identifying targets for improvement really is where the benefit lies in looking at this kind of information,” he added.

Different Paradigms in Europe, United States

But according to Dr. Roe and colleagues, the treatment paradigm for STEMI care is very different in the United States compared with Europe. Although exact numbers are unknown, they say anecdotal evidence and trial experience suggest that bypassing the ED is performed far more frequently at European hospitals. However, they also note that unlike most of the United States, European countries also have:

• Frequent physician staffing of ambulances
• Integrated EMS networks within single nationalized healthcare systems
• More robust information technology infrastructure to allow for digital transmission of prehospital ECGs for physician over-read
• Concentration of primary PCI procedures at highly experienced regional centers with high annual primary PCI volumes

Despite the differences, Dr. Roe and colleagues say, data indicate that bypassing the ED can be performed “reliably and safely in the [United States] when there is a substantial institutional and physician commitment to adopt this process.”

One potential concern, however, is the risk of bypassing ED evaluation during off-hours “when the primary PCI team may still be in transit to the hospital,”  Dr. Roe and colleagues note, although they suggest this problem “may be mitigated by developing overlapping in-house care team coverage for the time period of initial patient arrival.”

1. Bagai A, Jollis JG, Dauerman HL, et al. Emergency department bypass for ST-segment elevation myocardial infarction patients identified with a pre-hospital electrocardiogram: A report from the American Heart Association Mission: Lifeline program. Circulation. 2013;Epub ahead of print.
2. Antman EM. Bypassing the emergency department to improve the process of care for ST-elevation myocardial infarction: Necessary but not sufficient. Circulation. 2013;Epub              ahead of print.
3. O'Gara PT, Kushner FG, Ascheim DD. 2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: A report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013; Epub ahead of print.

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