ECG Blog #483 — This is Not a STEMI ...

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I am back from our vacation in the Canadian Rockies!

— Thank you all for your interest and support! —

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ECG Blog #483 — This is Not a STEMI ...

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The ECG in Figure-1 was obtained from a 60-year old woman — who presented to the ED (Emergency Department) with new CP (Chest Pain).

• How would you interpret the ECG in Figure-1?
• Would you activate the cath lab? If not — Why not?

Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio).

MY Thoughts on Today’s CASE:

Unfortunately — Details about this patient’s past medical history — as well as about the onset, severity and duration of this patient’s CP in association with this initial ECG in Figure-1 are not available.

• The above said — despite the ECG in Figure-1 not satisfying criteria for a STEMI (ST Elevation Myocardial Infarction) — the cath lab should be activated.

If there is reluctance to activate the cath lab on the basis of this initial ECG because the tracing in Figure-1 does not statisfy STEMI criteria — then the following measures should be immediately enacted:

• This initial ECG shoud be repeated within 10-20 minutes after recording this 1st tracing. This is because an acute evolving cardiac event will often show ST-T wave changes within minutes — especially if the nature and relative severity of CP is changing. If “dynamic” ST-T wave changes are seen on the repeat ECG in a patient like this with new CP — this is an indication for prompt cath!
• Find out about this patient’s prior medical history. Especially try to find a previous ECG for comparison (which can tell you if the ST-T wave changes seen in Figure-1 are new).
• Do an Echo at the bedside — which if associated with a localized wall motion abnormality during CP — is diagnostic of an acute event until proven otherwise. (NOTE — If no wall motion abnormality is seen on Echo, but the Echo was obtained at a time when the patient was not having CP — then this "negative" Echo does not rule out the possibility of an acute event. For an Echo to be optimally helpful — the patient should be having CP at the time the Echo is done).
• Realize that IF Troponin is at all elevated in a patient with ECG changes and new CP — that regardless of whether or not STEMI criteria are satisfied on ECG, this is indication for prompt cath. (Along the way — Be aware that the initial 1 or 2 hs-Troponin values may occasionally be normal IF the duration of acute coronary occlusion is brief).
• Be sure to correlate (and record on the chart) the presence and relative severity of CP (ie, on a scale from 1-to-10) — with each serial ECG that is done. Awareness that ST-T wave changes may improve (and even resolve) if CP decreases — and/or increase if CP increases — may prove invaluable for clinical correlation and optimal interpretation of your patient’s serial ECGs.

What the ECG in Figure-1 Shows:

Especially in view of the history (of new-onset CP) — there are a number of concerning findings in today's initial ECG that I highlight below in Figure-2:

• The rhythm is sinus — but at a tachycardic rate (of just over 100/minute). NOTE: Most of the time — an uncomplicated acute MI will not result in sinus tachycardia unless something else (ie, heart failure, cardiogenic shock) is going on.
• All intervals and the mean QRS axis are normal. Transition (where the R wave becomes taller than the S wave is deep) occurs early, with a taller R wave than S wave already by lead V2. This is followed by all positive QRS complexes beginning in lead V3 — and continuing through to lead V6.
• The most remarkable finding in Figure-1 — is diffuse ST depression in multiple leads (ie, BLUE arrows highlighting ST depression in leads I,II,III; aVF; and in leads V3-thru-V6). This diffuse ST depression is associated with ST elevation in lead aVR (RED arrows in this lead) — which together with the diffuse ST depression — qualifies as DSI (Diffuse Subendocardial Ischemia). 

There are 2 additional findings of note:

• Although the QRS complex in lead aVL is tiny — there is subtle-but-real ST elevation, followed by terminal T wave inversion in this lead (within the RED rectangle).
• In lead V2 — there is the suggestion of slight ST elevation with an upsloping ST segment (at least in several of the beats in this lead — as suggested by the RED arrows). This appearance in lead V2 is made more noticeable by sharp contrast with the distinct ST depression seen in the 4 remaining chest leads.

Figure-2: I've labeled today's initial ECG.

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PEARL #1: As is often discussed on this ECG Blog (See ECG Blog #400, among many others) — today's initial EMS ECG is remarkable for the presence of diffuse ST depression (seen here in 8/12 leads — as indicated by the BLUE arrows) — with ST elevation in lead aVR. But unlike posterior OMI (in which the degree of ST depression is greatest in leads V2,V3 and/or V4) — ST depression in Figure-2 appears to be maximal in inferolateral leads. This ECG pattern suggests DSI (Diffuse Subendocardial Ischemia) — and should immediately prompt the following differential diagnosis:

• Severe Coronary Disease (due to LMain, proximal LAD, and/or severe 2- or 3-vessel disease) — which in the right clinical context may indicate ACS (Acute Coronary Syndrome).
• Subendocardial Ischemia from another Cause (ie, sustained tachyarrhythmia; cardiac arrest; shock or profound hypotension; GI bleed; anemia; "sick patient", etc.).

To Emphasize: In a patient with new CP (such as in today's case) — the ECG pattern of DSI will often indicate severe coronary disease, but not acute coronary occlusion! 

• The above said — especially in view of the profound ST depression in so many leads in Figure-2 — severe coronary disease with potential need for acute reperfusion should be assumed until proven otherwise!

PEARL #2: As noted above — today's case features some additional findings beyond DSI. These include: i) The suggested finding of ST elevation in several of the beats in lead V2 (RED arrows in this lead) — but not in any other chest lead; and, ii) Subtle-but-real ST elevation in lead aVL.

• As discussed in ECG Blog #320 and Blog #324 — acute OMI of the 1st or 2nd Diagonal Branch of the LAD (Left Anterior Descending) coronary artery may produce the "South African Flag" (SAF) Sign on ECG. While the ECG in Figure-2 lacks the ST elevation in lead I of the SAF Sign — acute Diagonal Branch occlusion should be considered, possibly in association with underlying multivessel coronary disease, given how diffuse and extreme the ST depression is in this tracing.
• Perhaps the terminal T wave inversion that we see in lead aVL of Figure-2 is an indication of some spontaneous reperfusion (and perhaps this is the reason more frank ST elevation is not seen in lead V2?).

BOTTOM Line: Given the presentation of new CP in association with the worrisome ECG picture in Figure-2 — prompt cardiac cath is clearly indicated.

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CASE Follow-Up:

• Troponin was positive.
• Cardiology was consulted by emergency providers — with request to activate the cath lab. Unfortunately — cardiology refused to perform angiography because, "STEMI criteria are not met". The patient was diagnosed with an NSTEMI ( = Non-ST Elevation Myocardial Infarction) — and medically treated accordingly. She remained in the ED for over 10 hours until her condition suddenly deteriorated, leading to cardiac arrest in the ED.
• Emergency cardiac cath was performed — which revealed a proximal LAD occlusion. Shortly thereafter a 2nd cardiac arrest occurred. CPR was unsuccessful — and the patient succumbed.

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Acknowledgment: My appreciation to Tayfun Anil Demir (from Antalya, Turkey) for the case and this tracing.

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ADDENDUM (6/15/2025):

• For More Material — regarding ECG interpretation of OMIs (that do not satisfy millimeter-based STEMI criteria).

Figure-6: These are links found in the top menu on every page in this ECG Blog. They lead you to numerous posts with more on OMIs.

• In "My ECG Podcasts" — Check out ECG Podcast #2 (ECG Errors that Lead to Missing Acute Coronary Occlusion).
• In 'My ECG Videos" — Check out near the top of that page VIDEOS from my MedAll ECG Talks, that review the ECG diagnosis of acute MI — and how to recognize acute OMIs when STEMI criteria are not met (reviewed in ECG Blog #406 — Blog #407 — Blog #408).
• 
  
• Please NOTE — For each of the 6 MedAll videos at the top of the My ECG Videos page, IF you click on "More" in the description, you'll get a linked Contents that will allow you to jump to discussion of specific points (ie, at 5:29 in the 22-minute video for Blog #406 — you can jump to "You CAN recognize OMI without STEMI findings!" ).

P.S.: For a sobering, thought-provoking case discussed by cardiologist Dr. Willy Frick — with editorial Commentary by me at the bottom of the page (in the March 17, 2025 post) — Check out this case.

• As Dr. Frick and I highlight — not only is the current "STEMI paradigm" outdated — but in cases such as the one we describe, because providers waited until STEMI criteria were finally satisfied — cardiac cath and PCI were delayed for over 1 day.
• BUT — because the cath lab was activated within 1 hour of an ECG that finally fulfilled STEMI criteria — this case will go down in study registers as, "highly successful with rapid activation of the cath lab within 1 hour of the identification of a "STEMI". This erroneous interpretation of events totally ignores the clinical reality that this patient needlessly lost significant myocardium because the initial ECG (done >24 hours earlier) was clearly diagnostic of STEMI(-)/OMI(+) that was not acted on because providers were "stuck" on the STEMI protocol.
• The unfortunate result is generation of erroneous literature "support" suggesting validity of an outdated and no longer accurate paradigm.
• The Clinical Reality: Many acute coronary occlusions never develop ST elevation (or only develop ST elevation later in the course) — whereas attention to additional ECG criteria in the above references can enable us to identify acute OMI in many of these STEMI(-) cases.

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