The ECG in Figure-1 was obtained from a middle-aged woman — who presented to the ED (Emergency Department) for epigastric pain that had begun ~1 hour earlier.
- The epigastric pain began during dinner. She was diagnosed in the ED as having gastritis.
- The 1st Troponin was not elevated.
QUESTIONS:
- How would you interpret the initial ECG in Figure-1?
- Does the negative initial Troponin rule out an acute event?
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| Figure-1: The initial ECG in today's case — obtained from a middle-aged woman with epigastric pain. (To improve visualization — I've digitized the original ECG using PMcardio). |
ANSWERS:
- A negative initial Troponin value does not rule out an acute cardiac event. This is true even if a "hs" ( = high sensitivity) Troponin assay is used.
- Instances in which an initial Troponin value may be negative despite an acute, ongoing infarction — include IF the period of coronary occlusion is short (ie, because there has been spontaneous reperfusion of the "culprit" artery).
- The ECG in Figure-1 is not normal. Rather than gastritis — this initial ECG suggests an acute OMI (Occlusion-based MI) in progress.
QUESTION:
- Did you pick up all of the findings highlighted in Figure-2?
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| Figure-2: I've labeled abnormal findings on the initial ECG. How many of these findings did you identify? |
My Interpretation of the ECG in Figure-2:
The rhythm in Figure-2 is sinus, perhaps with some sinus arrhythmia given variability of the R-R interval in the chest leads. Intervals (PR, QRS, QTc) and the frontal plane axis are normal. There is no chamber enlargement.
Regarding Q-R-S-T Changes:
- Q waves — Narrow Q waves of uncertain significance are seen in each of the inferior leads. Tiny (probably septal) q waves are seen in lateral chest leads V5,V6.
- R Wave Progression — shows a somewhat abrupt, early increase in R wave amplitude between leads V1-to-V2 — although transition (where the R wave becomes taller than the S wave is deep) occurs normally between leads V3-to-V4.
- Considering the history of new epigastric pain (which can sometimes be a chest pain equivalent) — My “eye” was immediately drawn to the 3 inferior leads (within the RED rectangles in Figure-2).
- Each of the inferior leads show slight-but-real J-point ST elevation — with straightening of the ST segment takeoff — and — a wider-than-expected T wave base. In this patient with new symptoms — these ST-T wave changes have the look of hyperacute ST-T waves.
- Strong support that these inferior lead changes are “real” and indicative of inferior OMI — is provided by the reciprocal ST-T wave depression in lead aVL, with a biphasic terminal T wave (BLUE arrow within the BLUE rectangle in Figure-2).
- Normally — there should be slight, gently upsloping ST elevation in leads V2 and V3. This is absent in leads V2 and V3 in Figure-2 — in which this normal, upsloping ST elevation has been replaced by ST segment flattening (with a hint of J-point depression in lead V2).
- Lead V4 serves as a "transition" lead — showing nonspecific ST-T wave flattening. This is followed in lead V5 by ST segment straightening, with a hint of ST elevation and a hint of terminal T wave inversion.
- There is too much artifact in lead V6 to tell much.
Impression of ECG #1:
I interpreted this initial ECG in Figure-2, as highly suggestive of acute infero-postero-lateral OMI until proven otherwise.
- If providers were to have any doubt about the diagnosis — the ECG should be repeated within 15-to-20 minutes (or even sooner if there is a change in symptom severity).
- Additional Troponins should be drawn (sometimes it takes 2 or 3 samples with acute OMI until Troponin levels rise).
- Stat Echo at the bedside may be helpful if it reveals a localized wall motion abnormality (Remembering that a normal Echo is only helpful for making OMI less likely if obtained during symptoms).
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The CASE Continues:
- A 2nd Troponin assay was also negative.
- The patient's epigastric pain continued.
- The ECG was repeated ~2 hours after the initial tracing.
To facilitate comparison in Figure-3 — I've put both ECGs together.
- QUESTION: Has there been any change?
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| Figure-3: Comparison between the initial ECG — and the repeat ECG that was done ~2 hours later. The patient continued to have epigastric pain. |
KEY Point: Comparison between serial ECGs is best accomplished by putting both tracings together and looking at them lead-by-lead (as is easily done in Figure-3).
- I did not see any significant change in the limb leads.
- In the chest leads — the ST segment straightening in lead V2 now clearly shows ST depression in ECG #2.
- Leads V3 and V4 now show a hint of shallow T wave inversion.
- Lead V5 continues to show ST segment coving with slight ST elevation.
- The artifact that was seen in lead V6 of ECG #1 has disappeared. This now allows us in ECG #2 to appreciate comparable ST segment coving, if not slightly more ST elevation in lead V6 compared to lead V5.
Impression of ECG #2:
The patient continues to have epigastric pain — which given the findings in these 2 serial ECGs, is clearly a CP (Chest Pain) "equivalent" symptom.
- I interpreted the comparison between ECGs #1 and #2 as confirmation of ongoing acute evolutionary changes of infero-postero-lateral OMI.
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The CASE Continues:
- A 3rd Troponin was positive.
- The patient's epigastric pain decreased.
- A 3rd ECG was done (recorded ~2 hours after ECG #2).
To facilitate comparison in Figure-4 — I've put the 2nd and 3rd ECGs next to each other.
- QUESTION: Considering that ECG #3 was done ~2 hours after ECG #2 (and that the patient's epigastric pain is now less) — How would you interpret this 3rd ECG?
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| Figure-4: Comparison between the ECG #2 — and ECG #3 that was recorded ~2 hours later. The patient's epigastric pain had decreased at the time ECG #3 was done. |
ANSWER:
There are subtle-but-real changes between ECG #3 and ECG #4:
- The limb leads in ECG #3 — all show nonspecific ST-T wave flattening. Complared to ECG #2 — this represents a reduction in the hyperacute changes in virtually all limb leads.
- In the chest leads — the ST depression in lead V2 from ECG #2 has resolved. The hyperacute ST-T waves in leads V5,V6 are much improved, now without any ST elevation. Shallow T wave inversion is seen in leads V3-thru-V6.
- Impression: Especially given the reduction in epigastric pain — there has been significant improvement in the acute ST-T wave changes seen earlier, with T wave inversion in leads V3-thru-V6 representing reperfusion T waves.
- Cardiac Cath was performed — which confirmed LCx (Left Circumflex) occlusion, with involvement of 2 obtuse marginal branches. The patient was stented.
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Acknowledgment: My appreciation to Tayfun Anil Demir and Emine Karakaya (from Antalya, Turkey) for the case and this tracing.
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For More Material — regarding ECG interpretation of OMIs (that do not satisfy millimeter-based STEMI criteria).
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| Figure-5: 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!" ).
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