Prehospital ECGs and STEMI Receiving Centers

An important paper has been published that deserves to be read in its entirety.

Rokos IC, French WF, Koenig WJ, et al. Integration of pre-hospital electrocardiograms and ST-elevation myocardial infarction receiving center (SRC) networks: Impact on door-to-balloon times across 10 independent regions. J Am Coll Cardiol Cardiovasc Intervent 2009; 2:339346

Here are some highlights:

“There were 2,712 patients diagnosed with STEMI by PH-ECG. In the 2,053 (76%) who underwent PPCI, pooled data from all 10 independently managed regions demonstrated an 86% rate of D2B ?90 min. When assessed by individual region, the rate of D2B ?90 min ranged from 77% to 97%.

Further analyses of the entire 2,053 patient cohort undergoing PPCI demonstrated a 50% rate of D2B ?60 min, 25% rate of D2B ?45 min, and an 8% rate of D2B ?30 min. There was a 68% rate of E2B ?90 min in this study. The E2B times could be determined in 762 of 2,053 (37%) patients, because only 5 of 10 regions had records that included the time of the first PH-ECG consistent with STEMI.”

I am particularly impressed that half of all patients in the study had D2B times ? 60 minutes.

Based upon this successful SRC network experience across 10 independent regions, we propose 3 areas of focus as STEMI regionalization expands across the nation. In reporting time-zero for E2B, our analysis used the PH-ECG time as previously defined, whereas the most recent STEMI guidelines use time of EMS arrival on scene. In reality, the true patient-centered time-zero for STEMI systems is time of 9-1-1 call, and hence this time-point represents the ideal starting point of E2B that should be tracked in future analyses. Time of EMS alarm/dispatch (usually occurring within a few minutes of 9-1-1 call initiation) is generally documented by paramedics and represents a reasonable surrogate for this ideal time-zero.

I wholeheartedly agree. There’s also something else that needs to be said. What about those STEMI patients for whom EMS neglects to perform a PH12ECG? First-medical-contact is first-medical-contact, whether an ECG is performed or not. If the hospital neglects to perform a 12 lead ECG until 30 minutes after the patient’s arrival in the ED, they still have to report their D2B time (not their ECG-to-balloon time). EMS should be held to the same standard.

“Second, any STEMI registry supporting the AHA-ML initiative and tracking overall resource use needs to broaden its entry criteria as previously proposed. Subsequent events for all patients with a PH-ECG interpreted as presumed STEMI need to be prospectively tracked. This approach, as performed in our 10-region study, provides the true denominator of STEMI system activations.

Absolutely. Every patient counts.

“Third, minimizing false-positive CCL activations is of potential interest for both interventional cardiologists and hospital administrators. The automated computer algorithm was the most frequently used in this study of the 3 existing PH-ECG interpretation strategies, because it could be rapidly implemented across large EMS systems and was considered reasonably accurate. However, given the real-world occurrence of incorrect computer algorithm analyses for various technical reasons, some regions have taken a Bayesian approach and set strict criteria for paramedic diagnosis of STEMI and CCL activation. For other regions, PH-ECG activation of the CCL has evolved into a 2-step process in which the on-duty ED physician served as the filter after radio communication with EMS. The ED physician then decided in real-time (24/7) which pre-hospital “STEMI Alert” merits conversion to an in-hospital “Code STEMI” involving CCL activation before patient arrival and which patients need further assessment in the ED to determine whether CCL activation is warranted. Simultaneous use of all 3 PH-ECG interpretation strategies might be the best approach in the future, because evidence suggests that the accuracy of in-hospital Code STEMI activation can be further optimized by PH-ECG wireless transmission and physician interpretation. Further study is warranted.”

This is why paramedics need to be able to interpet a 12 lead ECG at a very high level. I, for one, am tired of hearing excuses. The National Standard Curriculum for Paramedic states that a paramedic should be able to:

  • Recognize the changes on the ECG that may reflect evidence of myocardial ischemia and injury.
  • Recognize the limitations of the ECG in reflecting evidence of myocardial ischemia and injury.

In spite of this, paramedics are not receiving adquate training in 12 lead ECG interpretation in school. It’s time for the National Standard Curriculum to specify exactly what kind of training is required, and those specifications ought to include axis determination, conduction abnormalities, differential diagnosis of tachycardias, STEMI recognition, the STE-mimics, and identifying AMI in the presence of baseline abnormalities.

How can anyone argue that paramedics don’t need to know this stuff?


  • Sonnet says:

    Thanks for this nice article

  • Tom,I just wanted to say thank you for your blog. You have not only taught me so much, but have also encouraged me to start my own blog. Thank you for making things so simple. I haven’t been able to stop reading from your site and promoting it to others. Check out my blog if you get a chance. It’s coming along, if you have any suggestions please share.Also check out the forums at, we could use someone of your caliber. My user name on there is FL_Medic, feel free to borrow any of my EKGs. Thanks,Adam

  • Tom B says:

    You’re welcome, Sonnet!

  • Tom B says:

    Adam -Thanks for the positive feedback! I really appreciate it. Your blog looks great! I’m looking forward to taking the time to read it carefully.It’s been a while since I checked out I’ll look for your ECGs! Tom

  • Tom,;=0Thanks!!Here is a link to my most recent strip. This was a good one, sparked some good discussion. Adam

  • Tom B says:

    Interesting ECG, Adam.This demonstrates how critically important it is to consider the history and clinical presentation, and why you should always look for reciprocal changes.Although reciprocal changes are not always present, they are present on this ECG in leads III and aVF.Thanks for sharing!Tom

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