ECG Interpretation: ECG Blog #461 — STEMI, LV Aneurysm or Neither?

I was sent the ECG shown in Figure-1 — initially without the benefit of any history.

How would you interpret this tracing?
— What is YOUR differential diagnosis of this tracing?

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

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The Obvious Concern:

I immediately realized the reason that I was sent this tracing: ==> there is ST elevation in the anterior chest leads!

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MY Initial Thoughts on Figure-1:

Looking systematically:

There is a regular sinus rhythm at ~85/minute (upright P waves in lead II — with a constant and normal PR interval).
The QRS is narrow (ie, not more than 1/2 a large box in duration).
The QTc is at most borderline prolonged.
The Axis is markedly leftward, as per a predominantly negative QRS complex in lead aVF. Criteria for LAHB (Left Anterior HemiBlock) are fulfilled — given the predominantly negative QRS in lead II (ie, indicating a frontal plane axis more negative than -30 degrees).

Regarding Chamber Enlargement:

Criteria for atrial enlargement are absent (Reviewed in ECG Blog #75). So, although there is a negative component to the terminal P wave in lead V1 — I favor undercalling LAA because of limited specificity for this amount of P wave negativity in V1 as an indication of LAA.
That said — voltage for LVH is markedly increased!

There is marked LVH:

I've reviewed criteria for LVH on many occasions (See ADDENDUM below — for review of LVH criteria that I favor — as well as ECG Blog #73 for full discussion).
As per Figure-5 (in the Addendum below) — S wave amplitude is markedly increased in today's ECG (attaining an S wave depth = 28 mm in lead V2 — and an S wave depth = 28 mm in lead V4 — as shown in Figure-2).
PEARL #1: Sometimes with LVH — instead of seeing tall R waves with LV "Strain" in the lateral chest leads — we see the "mirror-image" opposite picture in right-sided leads V1,V2 (ie, LVH may be manifested by deep anterior S waves — with ST elevation in leads V1,V2 and/or V3). This is precisely what we see in today's case!

Figure-2: Assessment of R wave and S wave amplitude in the chest leads is rendered difficult by marked overlap of complexes in several leads. To facilitate assessment — I've colored in selected R waves and S waves.

Completing our Systematic Approach (with Q-R-S-T Changes):

Q Waves — There is a tiny septal q wave in lead aVL — which is unlikely to be important. But there are large QS waves in anterior leads V1,V2,V3.
R Wave Progression — Because of these large QS waves in the anterior leads, there is poor R wave progression (with Transition delayed until between leads V5-to-V6).
ST-T Waves — I've drawn in the PR segment baseline in leads V1,V2,V3 of today's ECG to highlight the amount of ST elevation (RED arrows in Figure-3 indicating the J-point as the marker for judging the amont of ST elevation).
Elsewhere, the 3 inferior leads and lead V6 show nonspecific ST-T wave flattening. Finally, lateral leads I and aVL show subtle, shallow T wave inversion — which is consistent with a "strain equivalent" pattern (as I highlight in Panel B of Figure-6 in today's Addendum).

Figure-3: I've labeled the PR segment baseline and J-points in selected chest leads to highlight the amount of ST elevation.

Putting It All Together:

Today's ECG shows a sinus rhythm at ~85/minute — a borderline QTc — LAHB — marked LVH — and — QS waves in leads V1,V2,V3, with no more than a tiny r wave in lead V4 — plus, ST elevation that begins in lead V1 and extends through to lead V5. Clinically — this may indicate any of the following (See Figure-4):

i) Antero-Septal MI may have occurred at some point in time — as suggesed by QS waves in leads V1,V2,V3.
ii) That there is marked LVH is strongly suggested by the greatly increased chest lead QRS amplitudes (with S waves = 28 mm in leads V2 and V4 — as shown in Figure-4) — with a "strain equivalent" pattern in lateral leads I and aVL (BLUE arrows in these leads).
The anterior lead ST elevation may simply reflect LV "strain" in a patient with marked LVH, which when manifest by deep anterior S waves (rather than tall lateral R waves) — may produce a vector in which the hypertrophied, posterior-lying left ventricle opposes normal anterior forces, thereby reducing (and sometimes eliminating) anterior r waves.
PEARL #2: As shown within the RED insert in Figure-4 — In such cases, the ST-T wave changes of LV "strain" (that are usually seen in lateral leads) — may present a mirror-image opposite ST-T wave picture of "strain" in anterior leads. This may account for the anterior ST elevation seen in today's case (BLUE arrows in leads V1,V2,V3).
iii) There could be acute LAD (Left Anterior Descending) coronary Occlusion that is now superimposed on the ECG of a patient with longstanding LVH, perhaps with also previous anterior infarction.
iv) The findings in Figure-4 could reflect LV aneurysm.

Conclusion: As I contemplated today's tracing that I initially interpreted without the benefit of any history — I thought any of the above diagnostic possibilities might be present. Although I suspected that the ECG findings in Figure-4 were not acute — I was not at all certain of that suspicion from this single ECG.

Clearly — a detailed history would be needed for adequate clinical assessment. Does this patient have a history of cardiac disease? Did the patient have CP? (Chest Pain). If so — When did the CP begin? Was CP still present at the time that the ECG in Figure-4 was taken?
Can we find a previous ECG on this patient (looking to determine if the QS waves and ST elevation is new or old).
Especially if CP was ongoing — a repeat ECG is needed (looking for signs of acute evolution) — in addition to Troponins, Echo and further assessment until we can determine if an acute process is in progress.

Figure-4: I've labeled KEY findings in today's ECG.

CASE Follow-Up:

I later learned the history in today's case — which was that a middle-aged man with diabetes and hypertension — who presented to the ED (Emergency Department) for abdominal pain that had awakened him from sleep.

The patient was markedly hypertensive in the ED — but he did not have CP.
Chest X-Ray was normal.
Troponins were negative.
Echo showed significant LVH with normal LV function and no wall motion abnormality.
Radionuclide scan was negative for ischemia.
Previous ECGs were found in the patient's chart — which showed similar findings of marked LVH with anterior ST elevation attributed to LV "strain".
In Summary: The patient's abdominal pain was treated. An acute cardiac event was ruled out. Cardiac cath was not done.

"Take Home" Message: Anterior lead ST elevation does not necessarily indicate acute infarction when the patient has LVH that is manifest by deep anterior S waves. In such cases — the anterior ST elevation may simply reflect LV "strain" (as per the "Mirror Test" that is shown within the RED insert in Figure-4).

Further evaluation may be needed in such cases to clarify what may be "new" vs "old" (ie, To rule out a new acute event that could be superimposed on longstanding LVH).
KEY Point: Anterior ST elevation is unlikely to represent LV "strain" if anterior S waves are not larger than is usually expected (ie, if there is no LVH).

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Acknowledgment: My appreciation for the anonymous submission of today's case.

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Related ECG Blog Posts to Today’s Case:

ECG Blog #205 — Reviews my Systematic Approach to 12-lead ECG Interpretation.
ECG Blog #73 — Reviews "My Take" on the ECG Diagnosis of LVH.
ECG Blog #92 — Presents another perspective for ECG Diagnosis of LVH.
ECG Blog #424 — Another example of when marked LVH may manifest anterior ST elevation.
For cases similar to today, in which LVH may mimic ischemia — Check out My Comment at the bottom of the page of the following posts in Dr. Smith's ECG Blog — the November 29, 2023 post — June 20, 2020 — March 31, 2019 — March 29, 2019 — and the December 27, 2018 post.
ECG Blog #218 — Reviews HOW to define a T wave as being Hyperacute?
ECG Blog #230 — Reviews HOW to compare Serial ECGs (ie, "Are you comparing Apples with Apples or Oranges?").