What if your system adopted the recommendation that a computer "normal" ECG need not be shown to the doctor?

Written by Pendell Meyers with edits by Smith.  Sent by anonymous

A man in his 40s with no previous heart disease presented within 30 minutes of onset of acute chest pain that started while exercising. There was associated shortness of breath and left arm radiation. 

This Triage ECG (ECG #1) was recorded on a chest pain patient at triage at 1906 (top highest quality image, bottom photo including computer algorithm interpretation):

"Sinus rhythm, normal ECG" (This was performed on a Mortara machine, most likely using Veritas algorithm, but I do not have perfect confirmation of that)

This ECG shows an obvious inferior acute coronary occlusion (OMI).  It is clearly missed by the conventional algorithm.  

Many systems now refrain from showing computer "normal" ECGs to the busy emergency physicians at triage because of very poorly conceived articles that say that if the computer algorithm says "normal," the emergency physician should not be bothered.  

Luckily, this institution does show all triage ECGs to the physician, who in this case immediately recognized OMI and activated emergent transfer to the local PCI center.

Here is the ECG interpreted by the Queen of Hearts:

Click here to sign up for Queen of Hearts Access

Here is ECG #2 at 1959 (I believe this is the time of arrival to the PCI center): 

Again, outrageous conventional algorithm interpretation!
Now it is a full blown STEMI of 3 myocardial territories: inferior, posterior, and lateral
But at least it does not call it "Normal."

Queen of Hearts:

The initial troponin (high sensitivity troponin I) returned less than 6 ng/L.  Below the limit of detection.

Angiogram findings included:

95% mid RCA stenosis with occluded distal right PDA secondary to thrombus (peristent OMI). Successful drug-eluting stent placement opening up 95% mid RCA stenosis to 0% residual

Nonobstructive left system disease. 

Left-ventriculogram showed severe infero-apical hypokinesis with LV ejection fraction 50 to 55%. LVEDP 25.   This is a significant loss of myocardium and ejection fraction.  Some function might possibly recover over weeks.

Medical therapy for thrombotic occlusion of distal right PDA.



Formal echocardiogram:

Systolic function is at the lower limits of normal. The ejection fraction is 50% +/- 5% , calculated using biplane MOD. Severe hypokinesis of the mid-apical inferior and inferoseptal myocardium.


Troponin trend:
less than 6 ng/L
933 ng/L

13,386 ng/L, typical of STEMI

(none further measured -- it might have peaked at a much higher level if it had been measured to peak)

Repeat ECGs after PCI:

These are diagnostic of reperfusion.

The patient was discharged home the next day. No further follow up is available.

Learning Points:

You cannot trust conventional algorithms even to find STEMI(+) OMI, even when they say "normal ECG." We have shown many examples of this on this blog.

Queen of Hearts is available and performs well.

Click here to sign up for Queen of Hearts Access

You should not wait for the troponin when the history and ECG is diagnostic. Even in obvious STEMI(+) OMI, the initial troponin can easily be negative in the initial short time from onset of OMI.

The Queen of Hearts diagnoses almost all of these so called "Normal" ECGs with are in fact OMI and she does so with High Confidence:  

See this post of 10 cases:

When the conventional algorithm diagnoses the ECG as COMPLETELY NORMAL, but there is in fact OMI, what does the Queen of Hearts PM Cardio AI app say? (with 10 case examples)

See other relevant posts:

An undergraduate who is an EKG tech sees something. The computer calls it completely normal. How about the physicians?

Three patients with chest pain and “normal” ECGs: which had OMI? Which were normal? And how did the Queen of Hearts perform?

Four patients with chest pain and ‘normal’ ECG: can you trust the computer interpretation?

Chest pain and a computer ‘normal’ ECG. Therefore, there is no need for a physician to look at this ECG.

And literature:

McLaren, Meyers, Smith and Chartier. Emergency department Code STEMI patients with initial electrocardiogram labeled ‘normal’ by computer interpretation: a 7-year retrospective review. Acad Emerg Med 2024;31:296-300

 

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MY Comment, by KEN GRAUER, MD (6/11/2024):

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Recognition of repolarization variants can be challenging. At times, the distinction between a repolarization variant vs the early stage of acute OMI may not be possible solely on the basis of a single ECG.

• To add to this complexity (as per My Comment in the August 22, 2020 post in Dr. Smith's ECG Blog) — the ST-T wave appearance in repolarization variants may be dynamic! On occasion — ST-T wave appearance with repolarization variants may change from one-hour-to-the-next — or, ST-T wave appearance may change due to a difference in heart rate, performance of exercise, or variation in vagal tone — and, sometimes even without any obvious explanation.
• Finally — there is the clinical reality that a patient who has a "baseline" ECG that manifests a repolarization variant — may at some point develop acute coronary occlusion that in part is masked by benign-appearing ECG characteristics of the underlying repolarization variant.
  

 

It is for the above reasons that I was at first uncertain about the ST-T wave appearance in the inferior leads of the initial ECG in today's case (within the light BLUE rectangles in leads II,III,aVF in Figure-1).

• Although the amount of J-point ST elevation in leads II,III,aVF in Figure-1 is more than is usually seen with repolarization variants, and the peak of the T wave in these leads seemed "bulkier" than usual — the upward-concavity shape of the ST segment (ie, "smiley"-configuration) was not unlike that seen in many repolarization variants.
• Small and narrow q waves are seen in each of the inferior leads of ECG #1 — but in this patient with a relatively vertical frontal plane axis, narrow inferior lead q waves are a common normal manifestation of septal depolarization.
• BOTTOM Line: I would not have diagnosed an acute OMI on the sole basis of inferior lead appearance in today's initial tracing.
  

KEY Point: Despite what I felt was the nondiagnostic picture presented by the ST-T wave appearance in leads II,III,aVF — Definitive ECG diagnosis of an acute OMI is present in ECG #1 for the following reasons:

• The clinical history immediately places today's patient in a higher-prevalence group of patients likely to be evolving an acute OMI (ie, a middle-aged man who presents to the ED for new-onset CP [Chest Pain] that occurs during exercise, and lasts for at least 30 minutes!).
• There is no way the ST-T wave appearance in lead aVL can be normal (within the RED rectangle in this lead). True reciprocal ST-T wave depression does not develop with repolarization variants. While some T wave inversion may normally be seen in lead aVL when the QRS is predominantly negative — there should not be J-point depression in such cases (the RED arrow in lead aVL) — and the inverted T wave should not be as "bulky" as it appears to be in lead aVL of ECG #1.
• Once we know in this patient with new CP that the ST-T wave appearance in lead aVL is definitely abnormal (and consistent with reciprocal ST depression) — we then have to presume that the upward-concavity ST elevation in each of the inferior leads is not simply due to a repolarization variant — but instead, must be interpreted as an acute inferior OMI until proven otherwise.
  
•  
• PEARL: Acute posterior involvement is a common accompaniment of acute inferior OMI. Therefore, the fact that the limb leads show an acute inferior OMI — should prompt us to carefully scrutinize anterior leads for any suggestion of posterior involvement.
  
• Having said this — there is no way the ST-T wave appearance in lead V3 of ECG #1 can be normal (within the RED rectangle in this lead). As we often emphasize on Dr. Smith's ECG Blog — there is normally slight, upward sloping ST elevation in leads V2 and V3. The RED arrow in lead V3 highlights the isoelectric (ie, non-elevated) baseline of the J-point in this lead — which in the context of the above ECG findings, strongly suggests acute posterior OMI until proven otherwise.
  
• By the concept of neighboring leads — I strongly suspected that the ST-T wave appearance in lead V2 was also abnormal because: i) There is no more than the most minimal J-point elevation in this lead; and, ii) The T wave appears more pointed than expected (potentially suggesting some posterior reperfusion).
• To EMPHASIZE: I would not perceive lead V2 by itself to be abnormal (especially given how deep the S wave is in this lead) — but because the history and limb lead appearance are diagnostic of acute inferior OMI — and — because lead V3 truly suggests associated acute posterior involvement — I suspected that the subtle changes in lead V2 were probably also abnormal.

Figure-1: I've labeled the initial ECG in today's case — and compare it with the repeat ECG done 53 minutes later.

What Do We Learn from ECG #2?

The diagnosis of acute infero-postero-lateral OMI becomes obvious with the evolution seen in ECG #2: 

• The ST elevation in the inferior leads of ECG #2 has increased — and the shape of this ST elevation has clearly taken on a more acute appearance.
• There is more ST depression in lead aVL — and the shape of this reciprocal ST depression has taken on a "shelf-like" appearance.
• The peaked T wave previously seen in lead V2 has been replaced by ST depression. The upright T wave seen in lead V1 of ECG #1 is also gone.
• There is now frank ST segment straightening, with some definite ST elevation in leads V3-thru-V6.

 

At this point — a STEMI was diagnosed, and cardiac cath with PCI was performed.

• Given the history of new-onset worrisome CP — the initial ECG in today's case was diagnostic of acute infero-postero OMI for the reasons detailed above.
• The fact that the initial troponin was normal does not in any way rule out acute OMI — as the initial troponin is not always elevated.
  
•  
• KEY Point: The comparison between ECG #1 and ECG #2 done just 53 minutes later — shows a dramatic change! Significant ST-T wave abnormalities may evolve over a period of minutes in an actively ongoing OMI. If either the initial ECG in today's case was not recognized as diagnostic of acute OMI — or — the interventionist cardiologist On-Call could not yet be convinced of the need for prompt cath from the initial ECG — it is likely that a repeat ECG done much sooner than 53 minutes later would have satisfied their criteria for cath.
• In cases like this — repeating the ECG every ~10-20 minutes until there are ECG changes sufficient for the patient to be accepted for cath is advised.