Early Repol vs STEMI

[NPO]

How can I tell early repolarization from a stemi. Let's assume the patient is of a relevant age. Let's say 50 year old male.

Is it even something that should be considered for prehospital transportation?

Mostly I'm just curious.

 

[Merck]

Yes you can learn to tell in the prehospital setting, however like most things it's open to interpretation so the more practice and experience the better.

Is it relevant? Certainly. On the one hand calling something a STEMI and activating the cath lab and being wrong is embarrassing and cost some $. On the other side calling something BER and disregarding can cost much more...

I'd urge you to bring up the need for education with a medical director. ECGs aren't the be all and end all of prehospital medicine. More goes into a diagnosis (thought they can be pretty convincing).

 

[Aprz]

Typically you won't see reciprocal changes (ST depression and inverted T waves) in early repolarization. If anything, ems12lead has really been pushing looking at lead aVL for reciprocal changes lately.

Some authors have suggested that the first sign of acute inferior STEMI is a downsloping ST segment in lead aVL, and I have seen this happen many times.

http://ems12lead.com/2008/12/contiguous-and-reciprocal-lead-charts/

The QTc will usually be short, but some STEMI-mimics like LVH and LBBB will also increase the QTc. I consider normal QTc to be less than 420 ms, but just because it's less than 420 ms doesn't rule out STEMI.

The QTc is almost always prolonged in the setting of ischemia.

http://ems12lead.com/2011/05/53-year-old-male-with-a-suspicious-ecg-conclusion/

The ST elevation (STE) will be upwardly concave instead of convex.

There is sometimes notching at the J-point.

Look at this image. 2nd box has notched J-point. 3rd box has upwardly concave STE.

That image is from ems12lead.com. The image is actually going over pericarditis, but notching of the J-point and upwardly concave STE are also commonly found in early repolarization too.

Lack of "hyperacute" large T-waves.

http://cdn.lifeinthefastlane.com/wp-content/uploads/2010/11/Anterior-STEMI-.jpg

http://lifeinthefastlane.com/ecg-library/basics/t-wave/

There are a lot more ways to differentiate early repolarization from STEMI. Some blogs have dedicated most of their time to this. You could literally write a book on it.

I highly recommend checking ems12lead, lifeinthefastlane, and Dr. Smith's ECG Blog. I'd also practice daily at least one 12-lead. I listed many ECG websites in our 100% Directionless thread.

Harvard's ECG Wave Maven
TomB's (Tom Bouthillet) Blog - EMS12Lead
Christopher's Blog - Six Letter Variable
KellyBracket's (Dr. Brook Walsh) Blog - Mill Hill Ave Command
Dr. Amal Mattu's EKG Video
Dr. Smith's ECG Blog
Learn the Heart - EKG Quizzes
ECG Learning Center
Facebook - The EKG Club
Facebook - ECG Problems
Dr. Ken Graur's ECG Blog / Dr. Ken Graur's Resources and Books
Dr. S. Venkatesan's Blog

Christopher, who also helps with ems12lead (editor and also post up some cases too I think?), I believe said paramedics should be able to interpret up to difficulty 3 ECGs from The Harvard ECG website.

Good luck!

 

[MSDeltaFlt]

How can I tell early repolarization from a stemi. Let's assume the patient is of a relevant age. Let's say 50 year old male.

Is it even something that should be considered for prehospital transportation?

Mostly I'm just curious.

Yes this is very important. Because if you don't know what early repolarization is then you will see STEMI when there isn't one and end up becoming just like the boy who cried wolf. To put it simply you can't have ST elevation without including the S wave. So ifthe ST "segment" is elevated but the S wave is not (as said "J point"), then all you have is an early repolariation and not a STEM in those leadsI. Now they can still be having an MI somewhere else by having STEMI without early repolarization in other leads or even have an NSTEMI. So still do a full patient assessment. But that is what early repolarization is.

 

[Craig Alan Evans]

There are many things that cause ST segment elevation and mimic an AMI. One of the keys in distinguishing between the two is the morphology of the T Wave. The T Wave of an acute MI has certain characteristics that when present are highly predictable.



The T Wave will first be hyper acute prior to ST segment elevation. Notice how it is asymmetrical and not very sharp or pointy looking as in hyperkalemia.



The first upstroke of the T Wave will transition from being concave in shape to straight or convex in shape as the ST segment elevates.

 

[Craig Alan Evans]

This concave vs convex has proven to be an excellent differential diagnosis using just a 12 lead. BER and pericarditis are both concave in shape while an AMI will always be straight or convex.

 

[Norbi]

Excuse me,what's BER?

 

[chaz90]

Excuse me,what's BER?

Benign Early Repolarization

 

[NPO]

Awesome information guys. With that and the links provided I should have plenty of material to read on duty today.

One of my supervisors is an AHA instructor too so I'll follow up with him one day too.

 

[TomB]

R-wave progression is one of the best tools to help distinguish early repolarization from LAD occlusion but, as others have indicated, absence of reciprocal changes is also important. Other indicators include a QTc on the short side of normal, well developed R-wave in lead V4, fish-hooked J-point (not always present), upwardly concave ST-elevation (be careful as this does not rule out STEMI).

Dr. Smith has a complex formula that seems to works very well.

(1.196 x STE at 60 ms after the J-point in V3 in mm) + (0.059 x computerized QTc) – (0.326 x R-wave Amplitude in V4 in mm)

A value greater than 23.4 is quite sensitive and specific for LAD occlusion.

Dr. Smith adds these qualifiers:

"It is critical to use it only when the differential is subtle LAD occlusion vs. early repol. If there is LVH, it may not apply. If there are features that make LAD occlusion obvious (inferior or anterior ST depression, convexity, terminal QRS distortion, Q-waves), then the equation MAY NOT apply. These kinds of cases were excluded from the study as obvious anterior STEMI. ST elevation (STE) is measured at 60 milliseconds after the J-point, relative to the PR segment, in millimeters."

 

[Handsome Robb]

This concave vs convex has proven to be an excellent differential diagnosis using just a 12 lead. BER and pericarditis are both concave in shape while an AMI will always be straight or convex.

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Do you have any links to articles, blogs or studies about this? Everything I've been taught agrees with what you said but I referenced the concave vs convex in a conversation with a physician the other day and he disagreed. Unfortunately we got pulled for a call so we didn't get to continue the conversation.

Not try to argue, I'm really interested in this. I've always felt 12-leads are a weak point for me.

 

[Christopher]

...while an AMI will always be straight or convex...

Not strictly true. It may be straight or convex, both of which are certainly more prevalent in AMI. But early AMI may have concave ST-segments.

 

[Christopher]

Do you have any links to articles, blogs or studies about this? Everything I've been taught agrees with what you said but I referenced the concave vs convex in a conversation with a physician the other day and he disagreed. Unfortunately we got pulled for a call so we didn't get to continue the conversation.

Not try to argue, I'm really interested in this. I've always felt 12-leads are a weak point for me.

ST elevation: differentiation between ST elevation myocardial infarction and nonischemic ST elevation (This paper is great except for one of the figures which shows a lead-swap, I've emailed Dr. Birnbaum about it; bonus points if you can tell me which ECG has the lead-swap; double bonus if you know which leads were backards)

The evolution of electrocardiographic changes in ST-segment myocardial infarction.

 

[Brandon O]

Just to round out the previous great remarks: there are a lot of little tricks and angles toward getting really amazing at distinguishing STEMI from other causes of ST changes. And sometimes you'll need them. But frankly, you can get pretty darn good numbers for simple BER vs STEMI if you just look for reciprocal changes -- carefully, diligently, and judiciously. They are not perfect for ruling STEMI either in or out, but they're pretty good in both directions, especially if you can recognize subtle changes and understand the anatomical patterns.

Reciprocal changes are very high-yield. They are easy. They work in a wide range of circumstances. They are your friend.

 

[NPO]

Well this has been very helpful. I am going to have to go learn about reciprocal changes now I suppose. I know the basics, but I want to really learn it too.

We were in an ER the other day with a patient and the EKG Tech walked up to do an EKG and I showed her the 12 that we had gotten on our guy. I had identified it as early repol, but wanted to check. She seemed to agree.

I'm only a basic, and in a very restrictive system, so this is all extra curricular. But if I can learn something, help my medic and prepare more for medic school, then cool. I just have to be careful not to become that dangerous EMT that THINKS he knows more than he does. :unsure:

As a result of this my partner has agreed to do at least one 12 lead per day for practice. He also suggested that we find a good (relevant) article or discussion every day to learn from or talk about when we have down time.

 

[Aprz]

I just have to be careful not to become that dangerous EMT that THINKS he knows more than he does. :unsure:

It's too late for me.

 

[Christopher]

Well this has been very helpful. I am going to have to go learn about reciprocal changes now I suppose. I know the basics, but I want to really learn it too.

My suggestion is to pick up a copy of Garcia and Holtz 12-Lead ECG: The Art of Interpretation.

It will walk you through it from beginner to advanced. Best book out there bar none.

We were in an ER the other day with a patient and the EKG Tech walked up to do an EKG and I showed her the 12 that we had gotten on our guy. I had identified it as early repol, but wanted to check. She seemed to agree.

A good habit to get into early is to make a list of what the ECG is definitely not and what the ECG could be ordered by likelihood. This will keep your brain from doing 1:1 pattern matching and leave you open to a range of diagnoses.

I'm only a basic, and in a very restrictive system, so this is all extra curricular. But if I can learn something, help my medic and prepare more for medic school, then cool. I just have to be careful not to become that dangerous EMT that THINKS he knows more than he does. :unsure:

I won't say who, but I know two EMT's who read ECG's better than most of the paramedics in my 7 county service area (and the physicians too). I would trust their ECG judgement any day of the week, and twice on Sunday.

As a result of this my partner has agreed to do at least one 12 lead per day for practice. He also suggested that we find a good (relevant) article or discussion every day to learn from or talk about when we have down time.

Once you finish Garcia and Holtz, or while you work through it, check out (Aprz linked to both of these earlier):

- Alan E Lindsay's ECG Learning Center
- Harvard's WaveMaven (400+ practice ECG's)

By the way, I already like your partner and I don't even know him. PM me and I'll send some cool introductory articles you guys can both benefit from.