I was sent the ECG shown in Figure-1 — told only that that this middle-aged woman noted chest tightness and nausea an hour earlier.
QUESTIONS:
- How would YOU interpret the ECG in Figure-1?
- — IF told that this patient arrested shortly after ECG #1 — Does this change your interpretation?
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| Figure-1: The initial ECG in today's case. (To improve visualization — I've digitized the original ECG using PMcardio). |
MY Initial Thoughts on Today's CASE:
To emphasize — the only information I was provided with was that this middle-aged woman had chest tightness and nausea about an hour before ECG #1 was recorded.
- PEARL #1: The importance of the History can not be overestimated. Knowing that this patient sought medical assistance because of "chest tightness" — immediately places her in a higher-risk prevalence group for having an acute event. As a result — our scrutiny of less marked ST-T wave changes is heightened.
- PEARL #2: If at all uncertain as to whether a patient with subtle ECG findings is having an acute event — Repeat the ECG soon! (ie, within ~10-20 minutes — continuing to repeat the ECG often until such time that you arrive at more certainty as to whether or not an acute event is evolving). In today's case — I believe the patient arrrested before a repeat ECG could be done.
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Regarding the ECG in Figure-1 that was sent to me ...
My Reply: "Since this patient is having chest tightness — this ECG is potentially worrisome.
- Leads V1,V2 may be placed too high on the chest. This is relevant to today's case — because IF the picture we see in V1,V2 is not accurate — then we may overlook posterior OMI.
- PEARL #3: While not 100% predictive — seeing a significant negative component to the P wave in these leads (as per the YELLOW arrows in Figure-2) — suggests that the V1,V2 electrodes may be placed 1 or 2 interspaces too high on the chest (See ECG Blog #274 — for more on too high placement of the V1,V2 electrode leads).
Continuing with My Reply regarding ECG #1:
- The rhythm is sinus at ~70-75/minute. Intervals (PR-QRS-QTc) are normal. The frontal plane axis is slightly leftward (negative QRS in aVF) — but not enough to qualify as LAHB (positive QRS in lead II) — thereby placing the axis at about -10 degrees. No chamber enlargement.
- There are no Q waves — and R wave progression is appropriate, with transition (where the R wave becomes taller than the S wave is deep) between leads V2-to-V3.
- PEARL #4: Normally in leads V2 and V3 — there should be slight, gently upslopinng ST elevation. As per PEARL #3 — We have lost the diagnostic utility of lead V2 (because of probable malposition of this lead). That said, as per the RED lines I have drawn in Figure-2 — the ST segment in lead V3 is inappropriately flat (if not, slightly depressed).
- PEARL #5: The BEST way to verify subtle abnormality in a given lead — is to carefully scrutinize neighboring leads to see if similar abnormalities are also seen there. As suggested within the BLUE rectangle — similar ST segment flattening with angulation between the end of the ST segment and the ascending limb of the T wave is seen in lead V4. Subtle-but-real ST segment straightening is also seen in leads V5 and V6.
- PEARL #6: The more leads there are that show ST-T wave abnormalities — the greater the likelihood that these ST-T wave abnormalities are of clinical significance (This is true even when these ST-T wave findings are subtle).
- KEY Point: In the absence of new chest tightness and the clearly abnormal ST-T waves in leads V4-thru-V6 — I would probably not have been impressed by the limb lead findings in Figure-2. But, given my heightened clinical suspicion — there is no denying ST segment straightening in leads I and aVL, as well as in the inferior leads.
- In the context of new "chest tightness" — I thought today's ECG was highly suspicious for an acute cardiac event.
- If feasible — it would have been helpful to obtain valid information from leads V1 and V2 — by repeating the ECG immediately after verifying electrode lead placement.
- I was suspicious of acute posterior OMI — because of maximal ST-T wave change in leads V3,V4 (See links to multiple posterior OMI cases below in the References).
- Given how commonly posterior and inferior OMI occur together (because of the common blood supply these areas of the heart share) — I interpreted the unexpectedly terminal T wave positivity in each of the inferior leads as a hyperacute change (with greatest disproportionality of T wave to QRS amplitude seen in lead aVF) — thereby suggesting acute infero-postero OMI.
- Finally — the fact that virtually all leads in Figure-2 manifest ST segment flattening and/or depression (with ST elevation in lead aVR) — suggests there is DSI (Diffuse Subendocardial Ischemia) from multi-vessel disease.
- BOTTOM Line: The above noted ECG findings are admittedly subtle. But in the context of new "chest tightness" — it can be understood why this patient arrested soon after this tracing was recorded.
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| Figure-2: I've labeled the initial ECG in today's case. |
CASE Conclusion:
The patient was successfully resuscitated — and was doing better on follow-up.- There are lessons to be learned from today's case ...
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Acknowledgment: My appreciation to Heba Metawea (from Dubai, UAE) for the case and this tracing.
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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 #193 — Reviews the basics for predicting the "culprit" artery (as well as reviewing why the term "STEMI" — should be replaced by "OMI" = Occlusion-based MI).
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- CLICK HERE — for my 6 new ECG Videos (on Rhythm interpretation — 12-lead interpretation with Case Studies for ECG diagnosis of acute OMI).
- CLICK HERE — for my 2 new ECG Podcasts (on ECG & Rhythm interpretation Errors — and — Errors in assessing for acute OMI).
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- Recognizing hyperacute T waves — patterns of leads — an OMI (though not a STEMI) — See My Comment at the bottom of the page in the November 8, 2020 post on Dr. Smith's ECG Blog.
- ECG Blog #433 — for another subtle OMI case!
- ECG Blog #294 — Reviews how to tell IF the "culprit" artery has reperfused.
- ECG Blog #230 — Reviews how to compare serial ECGs.
- ECG Blog #115 — Shows how dramatic ST-T changes can occur in as short as an 8-minute period.
- ECG Blog #268 — Shows an example of reperfusion T waves.
- ECG Blog #400 — Reviews the concept of "dynamic" ST-T wave changes (and also DSI = Diffuse Subendocardial Ischemia).
- ECG Blog #337 — A "NSTEMI" that was really an ongoing OMI of uncertain duration (presenting with inferior lead reperfusion T waves).
- ECG Blog #274 — How to tell if leads V1,V2 are misplaced.
- ECG Blog #351 — Blog #285 — Blog 246 — Blog #80 — for examples of acute posterior OMI.
- ECG Blog #317 — reviews another case regarding use (or not) of Posterior Leads.
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