Wednesday, March 9, 2022

Memorize the squiggly lines - it helps save lives.

Sent by Logan Stark, MD, written by Pendell Meyers

Dr. Stark sent me this ECG below and said "Curious on your thoughts without context."

Here is the PM Cardio version of this phone screenshot:

I replied:
"The concern without context would be possible LAD OMI signs. There is poor R wave progression, slight STE, hyperacute T waves in V2-V5, reciprocal STD in inferior leads."

He gave me the context:

A middle aged man had sudden chest pain and arrested in front of his family. His wife immediately performed CPR.

EMS arrived and defibrillated him. 

He was already awake and alert by arrival to the ED.

He had persistent chest pain.

Providers immediately recorded this ECG (same as the ECG above):

Around 20-30 minutes later, this ECG was recorded:

The patient was taken quickly to the cath lab where a 100% acute thrombotic LAD occlusion was opened and stented.

He survived. 

Learning Points:

ECGs can be very specific when it comes to many diagnoses, including OMI. As Dr. Smith says, it is usually the interpreter who is nonspecific, not the ECG.

(Until AI develops for ECG interpretation), you must simply memorize morphologies and patterns that correlate with OMI in order to learn it.

Acute LAD OMI diminishes the R waves in the anterior leads, which is why it was the most important variable in the 4-variable formula for differentiating normal variant STE from subtle LAD OMI. Myocardium that is ischemic cannot conduct the action potential as well, resulting in less R wave than previously.

If you memorize the squiggly line patterns of OMI, you will be able to see it much sooner  than STEMI criteria (and in many cases they never develop STEMI criteria).


MY Comment by KEN GRAUER, MD (3/9/2022):


Today's case provides yet another example of an ECG that is diagnostic of acute OMI (Occlusion-based MI) despite failure to meet STEMI criteria. 

  • On the one hand, the ECG findings in today's case are subtle. 
  • On the other hand — the ECG findings in today's case should not be subtle to the "experienced eye".

For clarity — I have reproduced and labeled KEY findings for the initial ECG in today's case (Figure-1).

Figure-1: The initial ECG in today's case (See text).

MY Thoughts regarding ECG #1:

I interpreted today's tracing in the same way Dr. Meyers did = in the absence of any clinical information.

  • The rhythm is sinus at ~85/minute. Interals (PR/QRS/QTc) and the frontal plane axis are normal (ie, about +20 degrees). There is no chamber enlargement.

Regarding Q-R-S-T Changes:

  • A large Q waves is seen in lead III. Tiny q waves are seen in leads I, II, aVL.
  • As per Dr. Meyers — R wave progression is poor, with no more than a small r wave up to lead V4. Transition (where the R wave becomes taller than the S wave is deep) — is delayed, and does not occur until leads V5-to-V6 (normally it occurs by lead V4 at the latest).
  • NOTE: By itself — The poor R wave progression we see in Figure-1 would not be diagnostic of acute OMI. But in association with the ST-T wave changes seen on this tracing — this clearly adds further support of an acute event in progress.

Regarding ST-T Waves:

  • KEY Point: Multiple leads in ECG #1 manifest ST-T wave abnormalities. Some are more subtle than others. In such cases — I often like to begin with those leads in which there is no doubt about the abnormality.

  • The 2 leads in ECG #1 that most caught my attention were leads V2 and V3. Although it is common to normally see a small amount of ST elevation in anterior leads V2 and V3 — the shape of the elevated ST segment in lead V2 is distinctly abnormal. Instead of gentle upsloping of the ST segment that is commonly seen with normal tracings (and/or with repolarization variants) — the ST segment "takeoff" is abnormally straightened (parallel to the angled BLUE line that I drew in this lead).
  • Although the J-point in lead V3 is not elevated — the angle of the straightened ST segment "takeoff" in this lead is even more acute than it was in lead V2.
  • In the context of the abnormalities just described for leads V2 and V3 — the subtle-but-real ST elevation and coved shape in lead V1 is clearly abnormal — and portends the marked ST elevation that will soon follow.
  • As per Dr. Meyers — there are hyperacute T waves in multiple chest leads. By "hyperacute" — we mean that: i) These T waves are taller-than-expected considering modest depth of chest lead S waves; ii) These T waves are fatter-than-expected at their peak; andiii) These T waves are wider-than-expected at their base. Stated another way — the T waves in leads V2-thru-V6 are all “more voluminous” than expected, and therefore hyperacute in a patient with new chest pain.

  • ST-T wave abnormalities are less pronounced in the limb leads — but nevertheless present in the inferior leads (abnormally scooped and depressed ST segments) — and in high lateral leads I and aVL (nonspecific, but definitely abnormal ST segment flattening).


  • Taken together (even before learning the history in today's case) — 11/12 leads show abnormal ST-T wave changes — with abnormal ST elevation already in leads V1,V2 — and with hyperacute T waves across the precordium. One has to assume acute LAD occlusion until proven otherwise!


YES — We have covered the topic of today's case many times before. But it always bears repeating. In Figure-2 — I list ECG findings, that when seen in association with new cardiac symptoms, are among those that suggest acute OMI despite not satisfying the millimeter-based definition of a STEMI.

Figure-2: ECG findings to look for when your patient with new-onset cardiac symptoms does not manifest STEMI-criteria ST elevation on ECG. For more on this subject — SEE the September 3, 2020 post in Dr. Smith’s ECG Blog with 20-minute video talk by Dr. Meyers on The OMI Manifesto. For my clarifying Figure illustrating T-QRS-D (2nd bullet) — See My Comment at the bottom of the page in Dr. Smith’s November 14, 2019 post.

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