ECG Patterns of Occlusion Myocardial Infarction: A Narrative Review
This was submitted by Hans Helseth, who is applying to med school and who is working as an EKG tech right now.
Smith: This patient presented years ago, but came in again while Hans was working. He looked back in time in the patient's chart and saw these ECGs and immediately recognized that they manifested subtle OMI.
Also: See Ken Grauer's excellent comments at the bottom.
Case
A 68 year old man with a medical history of hypertension, hyperlipidemia, and CAD with stent deployment in the RCA presented to the emergency department with chest pain. He developed it only 20 minutes prior to presentation while cutting branches outside. He had an EKG recorded right away.
EKG 1, 1646:
Smith: this is suspicious for a very subtle inferior OMI. There is minimal STE in inferior leads, but also with terminal QRS distortion and some reciprocal ST depression in aVL. Terminal QRS distortion is always abnormal in leads V2 and V3, but we have also found it to be useful in other leads, though not quite as specific. Although normal variant STE can have reciprocal STD in aVL
I want to mention that Hans saw this immediately. Pretty impressive for someone who has not yet attended med school, or even been a nurse or paramedic yet.
Back to the case
The conventional computer algorithm (Marquette 12 SL) diagnosed “Normal Sinus Rhythm, Normal ECG”. This interpretation was confirmed by the overreading physician. The EKG is not normal, however. There is ST segment straightening in the inferior leads. There is baseline wander in aVL which makes it difficult to assess for reciprocal changes, but behind the artifact, the first QRS complex in aVL shows probable ST depression. In a patient with new chest pain and multiple cardiac risk factors this EKG is very suspicious for inferior OMI, although it is extremely subtle and should be repeated to eliminate the artifact in aVL.
Queen of Hearts for EKG 1: Not OMI with high confidence
The first 4th generation troponin T (URL 0.05 ng/mL) was drawn at 1650 and resulted below the limit of detection. The patient was given nitroglycerin which partially alleviated the pain. He was worked up non-emergently in the ED with pain recurring and resolving multiple times during his stay. Another EKG was eventually taken. It is unclear if the patient had pain or not at this time.
EKG 2, 2122:
The computer algorithm called this EKG normal, and this interpretation was again confirmed by the overreading physician who noted no changes from EKG 1. Since EKG 1, however, the T waves in the inferior leads have become concave. If the patient’s artery was indeed occluded at the time of EKG 1, then his artery was most likely open at this time. This change further supports the case for an OMI diagnosis.
Another 12-lead was taken 44 minutes after EKG 2.
EKG 3, 2206:
While extremely subtle, the ST depression in aVL has worsened slightly since EKG 2. This EKG was again called normal by both the computer and the overreading physician, although in the context of the previous two tracings, this finding suggests re-occlusion of the culprit artery.
Queen of Hearts for EKG 3: Not OMI with high confidence
See this post, in which the first sign of inferior OMI is ST depression isolated to leads I and aVL: (https://hqmeded-ecg.blogspot.
And this post, in which T wave inversion isolated to leads V2 and aVL are the only signs of inferior OMI: (https://hqmeded-ecg.blogspot.
Despite an undetectable troponin and three “normal” EKGs, the nature of the patient’s symptoms and his positive cardiac history warranted concern for ACS. As such, the patient was placed on a heparin drip and transferred by ambulance to a cardiac cath-capable facility.
En route to the next hospital, the paramedics recorded another 12-lead tracing.
EKG 4, 2327:
In V2-V5, the T waves have begun to flatten and ST depression has begun to develop. The T waves in the inferior leads are becoming convex again. The computer algorithm (Glasgow) called this normal, but it is highly suggestive of inferior and posterior OMI. This suggests continued occlusion of the culprit artery.
On arrival to the cath-capable facility, another EKG was recorded.
EKG 5, 0028
This EKG in a patient with new chest pain and multiple risk factors, especially after examination of the previous 4 EKGs, is diagnostic of inferior and posterior OMI. The T waves in the inferior leads have once again lost their concavity. The ST depression in aVL is horizontal and the T wave is subtly terminally upright. There is slight ST depression in V3. The Marquette 12 SL algorithm called this EKG normal, and as with all previous EKGs, this interpretation was confirmed by the overreading physician.
Queen of Hearts for EKG 5: Not OMI with mid confidence; this is to say that she does NOT think this EKG is normal.
At 0120, a repeat troponin T was drawn: 0.13 ng/mL (this is elevated, and thus in this context is now diagnostic of acute MI)
At 0330, about 11 hours after presentation, the patient was taken to the cath lab:
There is a 99% occlusion of the proximal segment of the RCA with TIMI 2 flow. In this screenshot, a small amount of contrast can be seen opacifying the vessel distal to the lesion.After stent placement:
The vessel is now open with TIMI 3 flow, although it is diffusely diseased and the middle segment is ectatic.
Left ventriculography demonstrated inferobasal hypokinesis and an EF of 45%. The troponin peaked at 0.4 ng/mL, which is relatively low for OMI. The patient was lucky to have periodic spontaneous reperfusion.
A post-cath EKG was recorded at 0719:
The overreading physician confirmed this interpretation, adding that in comparison to EKG 5, “rate has decreased”.
While ST depression and T wave inversion persists in aVL, the T waves in inferior leads have become concave and slightly smaller in size. The T waves in the anterior leads are once again upright. These findings support inferior and posterior reperfusion.
Every 12-lead recorded on this patient during his presentation was called completely normal by all conventional computer algorithms and attending physicians involved in this man’s care. Only the Queen of Hearts alerted any concern about an EKG!
Three years later, the patient presented again to the ED with chest pain. Here is his EKG for this presentation:
It is now truly normal! He was found not to have OMI during this presentation.The progression of leads III and aVL can be appreciated below:
MY Comment, by KEN GRAUER, MD (1/15/2024):
Figure-1: I've labeled the initial ECG and the 1st repeat ECG in today's case. |
A 50-something male presented to triage with chest pain for one day.
An ECG was recorded quickly before any further history or physical exam:
When I saw this (presented at a conference), I immediately thought it looked like Thype 1 Brugada phenocopy (in other words, Type 1 Brugada ECG pattern). There is an rSR' in lead V1 without any spike of the R'-wave. The downsloping STE starts immediately from the peak, leading to an inverted T-wave. Lead V2 also has downsloping STE with an inverted T-wave.
There is also some STE in aVL, with reciprocal STD in inferior leads, highly suggestive of OMI. This is unusual for Brugada and so one must be very careful not to brush it off. It still could all be due to a proximal LAD Occlusion.
In spite of the unusual appearance of aVL and inferior leads, I still thoght it looked like Brugada, but further investigation is warranted:
Case continued:
Further history revealed cough and shortness of breath. The temperature was 39.5 C. A Chest X-ray showed infiltrates. Thus, another etiology of chest pain is found, and the fever suggests "fever-induced Brugada." The physician in charge quickly realized all this and did not activate the cath lab.
More ECGs were recorded:
18 minutes:
The Queen of Hearts was fooled, but with low confidence:
The initial troponin returned at less than 3 ng/L.
2 hours:
Again, V1 and V2 have Type 1 Brugada pattern (see criteria for Type 1 below)
To determine whether it is indeed Brugada or not, it is important to determine whether the QRS is actually prolonged or not.
If the QRS is prolonged, then the differential includes:
1. Hyperkalemia
2. Drug toxicity, especially diphenhydramine, which has sodium channel blocking effects, and also anticholinergic effects which may result in sinus tachycardia, hyperthermia, delirium, and dry skin.
----Other drugs with sodium channel blockade: Tricyclic antidepressants. They result in a large R-wave in aVR, but also usually have a wider QRS.
----Other sodium channel blockers, such as flecainide or cocaine.
However, if the QRS is not prolonged, then Brugada is likely, and in this case, Brugada uncovered by fever is the likely culprit.
Criteria for Type 1 Morphology:
1. R'-wave of at least 2 mm in V1 or V2
2. But no distinct R'-wave because the ST segment takes off at an angle from the peak
3. The ST segment is convex upward ("coved"). [They use terminology of "concave downward"]
4. The peak at the high takeoff does not correspond with the J-point. It is BEFORE the J-point, as measured in other leads (e.g. lead II across the bottom). See this demonstration.
5. Gradual downsloping of ST segment such that at 40 ms after the takeoff, the decrease in amplitude is less than 4 mm (in this example, it is less than 1 mm). In normal RBBB, the decrease in amplitude is much greater (see this example).
6. ST is followed by a symmetrically negative T-wave
7. "The duration of QRS is longer than in RBBB," and "there is a mismatch between V1 and V6." This criterion is perplexing and not well explained.
8. The downsloping should be such that the Corrado index is greater than 1.0 (see example above), which ensures that there is enough downsloping of the STE.
Corrado index is the ratio: [ST elevation at the J-point] divided by [ST elevation at 80 ms after the J-point]. A flat ST segment will have a Corrado index greater than 1.
See here for more detail, especially on Type 2 Brugada:
Case continued:
Next AM:
Continued Type 1 Brugada phenocopy
Day 2:
Now it has Type 2 Brugada Morphology!
See this post to learn more about Type 2 Brugada and its morphology:
There is a score called the "Shanghai score" (links to mdcalc online calculator) which calculates risk of Brugada. It is to be used when there is clinical suspicion of Brugada syndrome based on the ECG findings, and is based on:
1. ECG
1.a. Type 2 or 3 pattern that converts wth provocative drug challenge. +2
1.b. Fever induced Type 1 pattern: +3
1.c. Spontaneous Type 1 pattern: +3.5
2. Clinical History
2.a. of atrial fib/flutter at age less than 30: +0.5
2.b. syncope of unclear etiology: +1
2.c. Suspected arrhythmic syncope: +2
2.d. Nocturnal agonal respirations: +2
2.e. Unexplained cardiac arrest or documented VF/polymorphic VT: +3
3. Family History
3.a. None: 0
3.b-d. Unexplained sudden cardiac death (3 categories) (+0.5 - +2)
4. Genetic test result
For this patient, he gets 3 points for fever induced Brugada and zero points for other categories, for a total of 3, which results in "Possible Brugada Syndrome"
Course: The patient's pneumonia was treated and improved. He was hemodynamically stable for discharge. He was advised to aggressively manage hyperpyrexia in the future and avoiding sodium channel blocking agents.
Here are more cases of Fever-induced Brugada:
MY Comment, by KEN GRAUER, MD (1/13/2025):
Applying these Points to Today's Case:
Although Dr. Smith instantly recognized the Brugada-1 ECG pattern in leads V1,V2 of today's initial ECG — there were other essential findings in this tracing and in this case:
No matter how many times I have seen Brugada-1 and Brugada-2 ECG patterns — I still find myself referring back to the images in Figure-1:
Figure-1: Review of ECG Patterns in Brugada Syndrome (adapted from Brugada et al in JACC: Vol. 72; Issue 9; 2018) — A) Brugada-1 ECG pattern, showing coved ST-segment elevation ≥2 mm in ≥1 right precordial lead, followed by a negative T-wave. — B) Brugada-2 ECG pattern (the “Saddle-back” pattern) — showing concave-up ST-segment elevation ≥0.5 mm (generally ≥2 mm) in ≥1 right precordial lead, followed by a positive T-wave. — C) Additional criteria for diagnosis of a Brugada-2 ECG pattern (TOP: the ß-angle; BOTTOM: A Brugada-2 pattern is present if 5 mm down from the maximum r’ rise point — the base of the triangle formed is ≥4). |