The ECG in Figure-1 — was obtained on the scene by EMS (Emergency Medical Services). The patient was a man in his 90s, who ~1 hour earlier, noted the onset of severe CP (Chest Pain). He was hemodynamically stable — but clearly distressed with a sense of “impending doom” at the time ECG #1 was recorded.
- Despite the patient’s age — he was independent, lived alone, had good mental function — and had family support.
QUESTIONS:
- How would YOU interpret the initial ECG in Figure-1?
- Given the patient’s advanced age — Should the cath lab be activated?
- — OR — Are the QS waves in the chest leads indication of a completed infarction?
- Extra Credit: How many beats are seen on this ECG?
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| Figure-1: The initial ECG in today's case. |
MY Thoughts on Today's CASE:
The format for recording today's ECG is different than that used in most medical systems that I've encountered.
- As illustrated in Figure-2 — only 7 beats are seen. For clarity — I've numbered these 7 beats in each of the 4 groups of 3 leads.
- The advantage of this type of recording system is that for these 7 beats — we get to see QRS morphology for each of these 7 beats in each of the 12 leads.
- The disadvantage of this type of recording system — is that 7 beats is a very small sample for assessing events occurring on this ECG. For example — if the 1 PVC ( = beat #5) would not have occurred until 3 beats later, then we would not have seen any PVCs on this tracing.
- PEARL #1: My exposure over the past decade to numerous international ECG internet forums has taught me how numerous the different ECG recording formats are. It's worth routinely spending a few initial moments for verifying what recording format is used for the ECG you are about to interpret. With minimal practice — it becomes EASY to recognize the identical timing for each of the 7 beats in today's tracing — with the 5th beat always being the PVC (which confirms that this particular format only views 7 beats — but shows us QRS morphology for these 7 beats in each of the 12 leads).
Now that we have identified the recording format used for today's tracing — We can begin our systematic interpretation.
- Six of the 7 beats in today's tracing manifest a narrow QRS complex — that when measured, is irregularly irregular (ie, Although difficult to appreciate visually — caliper measurement reveals a variable R-R interval for the first 4 beats — with an obviously shorter R-R interval between beats #6 and 7).
- P waves are absent. This defines the rhythm as AFib (Atrial Fibrillation), here with a controlled ventricular response (ie, overall heart rate between ~70-to-100/minute).
- Beat #5 is a PVC (Premature Ventricular Contraction) — because it is early, not preceded by a P wave, and manifests a markedly wider and very different-looking QRS morphology in almost every lead compared to the other 6 beats.
- The QTc looks normal.
- There is no chamber enlargement.
Regarding Q-R-S-T Wave Changes:
- Q waves are present in leads III, aVF — with QS complexes in leads V1-thru-V5, with no more than a tiny initial r wave in lead V6.
- R Wave Progression — never occurs because of the persistence of these chest lead QS complexes.
- Regarding ST-T Wave Changes: There is marked ST elevation, with straightening of the ST segment takeoff in leads V2-thru-V6. This J-point ST elevation attains 2-3 mm for leads V2,V3,V4 — being slightly less than this in leads V5,V6. Given that ST elevation is usually not seen in lead V1 — the 1 mm of ST elevation seen in this lead in today's tracing is abnormal.
- ST-T waves in the limb leads are also abnormal. The much broader-than-expected and "fatter"-at-their-peak T waves in leads I, II and aVL are hyperacute. There is subtle ST elevation in lead aVF — and ST-T wave flattening in lead III.
- IMPRESSION: In this patient who presents with severe, new-onset CP — today's ECG is diagnostic of an extensive, ongoing antero-lateral STEMI.
CASE Follow-Up:
The decision was made not to activate the cath lab. Repeat ECG showed further progression of ST-T wave changes. The patient was at that point transferred for cardiac cath and PCI. Unfortunately the patient arrested before catheterization could be completed — and could not be resuscitated.
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| Figure-2: I've labeled today's ECG to illustrate that only 7 beats are seen. Did YOU notice the abnormal ST-T wave in the PVC? (within the BLUE rectangle in lead V3). |
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COMMENT:
- Advanced age is not a contraindication to cardiac catheterization. More important than chronologic age is functional status (This patient was living alone, fully independent, with good mental function and with family support).
- PEARL #2: The presence of Q waves (including deep QS waves — as are seen in leads V1-thru-V5 in Figure-2) — is not necessarily an indication of completed infarction or of permanent damage. Surprisingly — even large Q waves may develop in as short a time period as 1-to-2 hours. Such Q waves may sometimes regress — and even completely resolve. Comparison with a prior ECG would be needed in order to determine the presence and extent of any previous infarction — and clinical follow-up would be needed to determine whether any new Q waves will be permanent.
- PEARL #3: It may sometimes be difficult to distinguish between active, ongoing infarction — vs LV aneurysm that developed following a prior infarction — vs superimposed new infarction, that occurs on top of prior infarction. That said — the shape and relative disproportionality of the elevated chest lead ST-T waves in Figure-2 — compared to S wave depth in the leads being looked at, are diagnostic of an acute ongoing event until proven otherwise. The amount of J-point ST elevation with LV aneurysm is at most modest (clearly less than what we see in leads V2-thru-V5 of today's tracing) — and longstanding elevated ST segments typically do not manifest such straightening of the ST segment takeoff, as is evident in leads V2-thru-V6.
- The PVC within the BLUE rectangle in lead V3 of Figure-2 — illustrates a shape of ST elevation that simply should not be there for a PVC in the absence of an acute OMI.
- An example of a case in which the diagnosis of acute OMI was made purely by assessment of ST-T wave morphology in a PVC can be found HERE (See My Comment at the bottom of this page in the October 8, 2018 post in Dr. Smith's ECG Blog).
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Acknowledgment: My appreciation for this case that is anonymously contributed.
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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 — and on 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.
- Recognizing ECG signs of Precordial Swirl (from acute OMI of LAD Septal Perforators) — See My Comment at the bottom of the page in the March 22, 2024 post on Dr. Smith's ECG Blog.
- 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.
- ECG Blog #337 — A "NSTEMI" that was really an ongoing OMI of uncertain duration (presenting with inferior lead reperfusion T waves).
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