To Transmit Or Not

In previous posts, I wrote about paramedics’ ability to identify STEMIs and about the computer’s ability to identify STEMIs. My conclusions were that unless 12-lead interpretation is a major and continual focus of paramedic education and qualify assurance, paramedics’ ability to recognize STEMI will not be optimal. While most paramedics can easily identify an inferior STEMI, lateral and anterior can at times be more difficult, the lateral because it is often subtler and the anterior because it is often confused by the STEMI mimics. As far as the computer’s interpretation ability, while it can be used as an interpretation assist, and is constantly being improved, I don’t feel it is yet ready for prime-time. The software misses too many STEMIs and inaccurately calls too many nonSTEMIs as STEMIs. While the computer companies are working hard to improve their algorithm, they are just not there yet. Today I address the question of transmitting 12-leads. Should all paramedic services be required to have 12-lead transmission capability?

I admit I have had a small bias against transmission. The services I have worked for have not had the transmission capability (We are getting it very soon). In our area there are three hospitals that allow paramedics to activate the cath lab based on recognition, one that requires transmission for the hospital to preactivate the cath lab. Unless, the patient absolutely insists, I go to the other hospitals because I know I can get the patient to the cath lab quicker because those hospitals will activate in advance of our arrival at the ED based on my interpretation alone. I do also work for a hospital where half the STEMIs that come in are from services that transmit and the other half do not. Our best times are from the service that does not transmit, but just barely.

Transmission is not necessary for the obvious big I can see it from across the room STEMIs if you have a paramedic who can give a good patch and a doctor at the other end willing to trust the interpretation. Two hospitals in our state that have excellent door to balloon times (their medics go right to the cath lab) do not rely on transmission at all. But here is the question I wonder about. If you rely on paramedics alone, are paramedics more apt to only call in the obvious STEMIs? What happens to the patients with the more subtler STEMIs? Are they missed? I would like to see a study asking this question. I wonder about this because we have had an occasional hard time just getting paramedics to call in on obvious STEMIs. In hospitals that have 100% of their services transmitting, do they have fewer missed STEMIs than those hospitals where none of their services transmit? By missed STEMI I mean a STEMI that is not recognized until the hospital that shows the same morphology on the prehospital 12-lead as opposed to the ECG evolving into a STEMI after ED arrival. My guess is that the all transmission system, where paramedics are encouraged to send in borderline 12-Leads capture a greater percentage of STEMIs. But this is just a hypothesis. I await a study for verification.

What do I feel is the ideal system? Here it is:

1. Include 12-lead competency in all paramedic education and QA
2. Encourage medics to consider but not rely on computer interpretation.
3. Tell medics to call in not just definite STEMIs but possible STEMIs. There is no shame in being wrong.
4. Add transmission capability.

With these four components in place, no STEMI should fall through the cracks.


  • Brooks Walsh says:

    A project in Winnipeg, CA used direct transmission of EKGs directly to cardiologists’ Blackberrys. Real neat – they would discuss the patient and location, and if appropriate, lyse in the ambulance!

    So, out of all the ECGs transmitted, 5.7% of the ECGs initially diagnosed as non-STEMI (3% of total ECGs) were later found to actually be missed STEMIs. Another 13% of non-STEMIs progressed to STEMI by ED arrival.

    Check out

    • medicscribe says:

      Thanks Brooks, I read the study last night. Very interesting. I would like to see the ED doctor and the cardiologist getting the 12-lead each time it is transmitted. We have also explored having medics in services that can’t transmit, take a photo of the 12-lead with their cell phone and email it. The quality is quite good, but we haven’t instituted it yet. I recieve a copy of each 12-lead that comes into our hospital on my i-phone and the EMS Medical Director and I email each other with our calls/guesses. Some are obvious STEMIs, some are obviously not STEMIs, and some demand a fuller story or a look at an old ECG.

  • Many cardiologists don’t want the responsibility of interpreting the ECG on their smartphone, especially during off hours, and I can’t say that I blame them. It’s a huge responsibility to say, “I don’t think it’s a STEMI” and then go back to bed.

    If you call in our cardiologists in during off hours, they will tell you it’s not a STEMI — right after they perform an angiogram.

    No one is perfect at ECG interpretation. Not paramedics, not ED physicians, not cardiologists. All three miss STEMIs all the time (which are frequently called “Non-ST elevation myocardial infarction” so you’ll never hear about it unless you pull the charts, examine the ECGs yourself, and compare to the cath notes, if there are any).

    There are a growing number of so-called “STEMI Equivalents” (or low voltage “semi-STEMIs”) that do not meet the AHA criteria. This is a complex topic and what concerns me is the inherent lack of system-wide learning.

    Are EMS and Emergency Medicine learning from Cardiology? Are Emergency Medicine or Cardiology learning from EMS? Are EMS and Cardiology learning from Emergency Medicine?

    Do you think I’d win any friends if I brought a couple of charts up to the cath lab and said, “Hey, Dr. So-and-So, let me show you some acute posterior STEMIs you misdiagnosed as anterior ischemia”?

    In far too many of these studies the “gold standard” is the opinion of the invasive cardiologist. I would love to see the methodology to see how they determined that only 3% of NSTEMIs were actually missed STEMI.

    Says who and by what criteria?

    • medicscribe says:

      Thanks for the great post, Tom. I am struck by your comment about the cardiologists not wanting the responsibility to activate the cath lab based on reading the 12-lead on their phone. We are trying to get our paramedics to step up to the late and call in for cath lab activation when they have a STEMI, but it has been hard to do. They are reluctant on all but the obvious ones to be the ones who activated the cath lab and were wrong. At the same time, we are also trying to get the ED doctors to step up and activate the lab when a paramedic either sends in a 12-lead or calls in with a good strory and description. Same thing. Some of the docs are reluctant to be the ones to activate and be wrong. I see this particuarly happening at night and on weekends when it far more important timewise to get an early activation. Some doctors more than others want to wait to see the patient before calling in the team. In our area PCI centers, at least one of the hospitals has the ECGs go right to the cardiologists when they are transmitted. The same hospital won’t activate the cath lab without a transmission. At our hospital, the cardiologists leave the decision up to the ED doctors to preactivate. True, when they are in the hospital, they are often consulted and have the final say on the questionable cases. And sometimes, it is true, the arteries turn out to be clean.

      I think it is also true that there are few documented missed STEMIs in the hospital in the sense that to be a STEMI you have to go to the cath lab and have an occlusion found. Otherwise, it is a NSTEMI (elevated enzeyemes only). The STEMI judging criteria is time to balloon. Not how many who needed the balloon didn’t get it. If you know they need the balloon, then they get the balloon.

      One of our cardiologists says “If you are right in your STEMI ALERTS 100% of the time, then you are not doing your job.” There needs to be an certain amount of overtriage/overactivation, a certain amount of patients who turn out to have clean arteries.

      I also agree with you about the need for the medics/ED Doctors/Cardiologists to work together. You mention the STEMI Equivilents. Our EMS Medical Director and I had our cardiologists go out to one of our services to give a talk. They showed a slide of elavation in aVR with widespread depression, and talked about how serious this was. They called it as you know, a Left Main Equivilent. Niether my boss, an accomplished ED doctor or myself had ever heard of it. It was fascinating to learn. Currently in our area, we are working with the AHA’s Mission LifeLine to improve our STEMI systems and one of the big features is to try to get the three goups working together.

      I think a big part of that working together is for all parties to drop their reluctance to be occasionally wrong, to be afraid to be judged negatively by the others, and to always err on the side of the patient.

      Thanks again for your comments, Tom. You do an amazing job with your 12-lead education.

  • BadgerMedic says:

    Depending on which of our hospitals you transmit to, a 12-lead is initially only seen by the ED physician, and then not always an attending. This sometimes makes sending in a questionable 12-lead counterproductive; you are sending in a tracing you are suspicious about and would like a cardiologist to see, but when it is a new resident that receives it, he/she may not necessarily be the best person to listen to your concerns and make a decision.

    After arrival, I have pressed some of the receiving doctors to further investigate or send on the 12-lead to the Cardio folks if I believe there is a good possibility of an acute problem, yielding mixed results – sometimes they will listen to my case, other times I’ve received a brush-off.

    In the end, I still do believe in transmitting ‘close’ or suspicious 12-leads to the hospitals – and following up those with discussing your concerns enroute.

  • BadgerMedic says:

    The other part about transmitting that I forgot, but you hit on was the ability to look up old ECG’s and look for changes. That can be the convincing argument for activation on those ‘close’ ECG’s.

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