The patient in today's case is an older man who called EMS for new CP (Chest Pain) — only to suffer witnessed cardiac arrest as the paramedics arrived on the scene. The patient was successfully resuscitated, and his initial ECG (shown in Figure-1) — was transmitted to the nearest cath-capable facility.
Treating clinicians (including the on-call cardiologist) refused to activate the cath lab on the basis of ECG #1 — saying, "There is no evidence of an acute STEMI, therefore no need for prompt cath with PCI".
QUESTIONS:
- Do YOU Agree with the above interpretation of ECG #1?
- Should the cath lab have been immediately activated?
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| Figure-1: The initial ECG in today's case. |
Need for Prompt Cath and PCI after Cardiac Arrest?
Because of how often the question arises as to the need for prompt cath with PCI following successful OHCA (Out-of-Hospital Cardiac Arrest) — I've copied my initial comments from ECG Blog #434:
- There are different approaches regarding decision-making as to which patients with ROSC (Return Of Spontaneous Circulation) following OHCA should undergo prompt cardiac catheterization. What does appear to be clear — is that the post-ROSC ECG helps to identify which patients are at highest risk, and who therefore may benefit from coronary reperfusion (Gentile et al — JAHA 12:3027923, 2023 — and — Baldi et al — JAMA Netw Open 4(1): e2032875, 2021).
- Prompt cath is advised if the post-ROSC shows an acute STEMI.
- The decision of whether to cath patients with a less definitive post-ROSC ECG is less clear. Waiting a few extra minutes to repeat the ECG in such patients may help reduce false positive results when there are equivocal findings on the initial post-ROSC tracing.
- — "MY Take" — It seems to be common sense that even if millimeter-based criteria for a STEMI are not present — that IF there are other ECG criteria indicative of acute coronary occlusion as the cause of OHCA — that prompt cath is not only reasonable, but should be advised.
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The Post-ROSC ECG in Today’s CASE:
The initial ECG following ROSC in today’s case is clearly abnormal. I’ve highlighted KEY findings in Figure-2.
- Although there is significant baseline artifact in the limb leads of ECG #1 — the underlying rhythm is sinus — as conveyed by the presence of upright P waves with a constant and normal PR interval in lead II. The rhythm is regular at ~100/minute ( = sinus tachycardia).
- The QTc appears to be slightly prolonged (although more difficult to assess given the rapid heart rate). The frontal plane axis is normal (+70 degrees). There is no chamber enlargement.
- There are tiny Q waves in leads III and aVF — which is not necessarily abnormal given the vertical axis.
- R wave progression is slightly delayed — with transition (where the R wave becomes taller than the S wave is deep) only occurring between lead V4-to-V5. That said, a definite initial positive deflection (r wave) is present in leads V2 and V3, with slight increase in size in lead V4 — so the significance of this finding is uncertain from this single ECG.
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| Figure-2: I've labeled key findings in today's initial ECG. |
The KEY to assessment of ECG #1 regards ST-T Waves:
- The most striking findings are in lead aVL (within the RED rectangle in Figure-2) — in which there is coved ST elevation with straightening of the ST segment takeoff, followed by terminal T wave inversion.
- PEARL #1: Because of the small size of the QRS complex in lead aVL — the above noted abnormal ST-T wave findings are admittedly subtle. That said — the height of the hyperacute T wave in lead aVL matches the height of the r wave in this lead — and there is no denying the subtle-but-real terminal T wave inversion in aVL, which is never normal when following a hyperacute T wave.
- PEARL #2: Any doubt about the validity of the ST-T wave picture in lead aVL should be immediately resolved on seeing the abnormally straightened and depressed ST segments in each of the inferior leads (within the BLUE rectangles). In view of the terminal T wave positivity in leads II,III,aVF — these inferior leads manifest the mirror-image opposite picture of the elevated ST segment with terminal negativity seen in lead aVL ( = true reciprocal changes).
- PEARL #3: It's important to appreciate in this older man with new CP, that IF we stopped here — the subtle-but-real ST elevation in lead aVL with indisputable reciprocal ST-T wave changes in each of the inferior leads is already diagnostic of an acute OMI until proven otherwise. That said, the fact that these limb lead ST-T wave changes are so suggestive — needs to increase our scrutiny of chest lead findings!
- PEARL #4: Aren't the T waves in leads V2,V3,V4 (and probably also in lead V5) a bit "bulkier" than expected? By this I mean that the T waves in these leads look "fatter"-at-their-peak and wider-at-their-base than expected given modest amplitude of the QRS complex in these leads (BLUE arrows in Figure-2). Although admittedly subtle — in the context of this older patient with new CP and indisputable acute findings of ST elevation in aVL (with reciprocal ST depression in the inferior leads) — I interpreted these chest lead findings as suggestive of hyperacute T waves in multiple chest leads, consistent with acute LAD (Left Anterior Descending) OMI until proven otherwise.
- To Emphasize — It can be challenging to determine what does and does not constitute a "hyperacute" T wave. Admittedly, this assessment is at times subjective (See ECG Blog #183 and ECG Blog #218 for more on this topic). The "good news" — is that practice increases one's comfort with recognizing when a given T wave is hyperacute. Ultimately — You can check yourself to see if what you thought was a "hyperacute" T wave, went on to evolve frank ST elevation in subsequent serial tracings.
- The ST segment in lead V1 is coved, and ever-so-slightly elevated. Considering small size of the QRS in this lead — this is not a normal appearance for the ST-T wave in V1.
- In lead V6 — the ST segment is straight and appears to be slightly depressed. This differs from the appearance of the ST-T wave in neighboring lead V5.
- As discussed in ECG Blog #380 — in the setting of acute LAD OMI, the finding of ST elevation in lead V1 (especially when V1 manifests a different ST segment shape than the shape of the ST segment in other anterior leads) — plus — ST depression beginning in lead V5 or V6 — suggests the presence of precordial "Swirl" in Figure-2 (ie, in which the site of LAD occlusion is so proximal as to result in ischemia of the septum).
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To Emphasize: It only took seconds for me to arrive at my presumptive diagnosis of an acute OMI — simply by: i) Knowing that this older patient had new CP severe enough to call EMS; and, ii) Recognizing the presence of clearly acute ST-T wave changes within the 2 colored rectangles in Figure-2 (ie, in leads II,III,aVF and aVL).
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Today's CASE Continues:
Given the ECG findings in Figure-2 and the witnessed cardiac arrest — the EMS team felt justification of prompt cath with PCI was established.
- Unfortunately — it would take more convincing of the emergency physician and consulting cardiologist that cardiac cath was needed, because "ECG #1 did not satisfy criteria for a STEMI".
For clarity in Figure-2 — I've put the repeat ECG together with the initial ECG done 36 minutes earlier.
QUESTIONS:
- In light of the initial ECG — How would YOU interpret the repeat ECG done 36 minutes later?
- Was I correct in my suspicion that the T waves in the initial ECG were hyperacute?
- Do the PVCs in ECG #2 provide additional information?
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| Figure-3: Comparison between the 2 ECGs in today's case. |
ANSWERS:
The underlying rhythm in today's repeat ECG is sinus. There are frequent PVCs — which appear to have a fixed coupling interval. Focusing on the sinus-conducted beats — there appears to be somewhat less ST depression in the inferior leads of ECG #2, as well as a less hyperacute appearance to the ST segment in lead aVL. But a very different impression is provided by what occurs in the chest leads!
- RED arrows in Figure-4 highlight ongoing evolution of the proximal LAD OMI. Thus, there is more ST elevation in lead V1 of the repeat ECG — new straightening of the ST segment takeoff in leads V2,V3,V4 — definite ST elevation now in leads V2,V3 — and clear increase in the hyperacute appearance of the more "voluminous" ST-T waves in leads V2-thru-V6.
- PEARL #6: Lead-by-lead comparison of the ST-T waves in the 2 ECGs in Figure-4 confirms my earlier suspicion that T waves in the chest leads of ECG #1 were indeed hyperacute!
- PEARL #7: As I illustrated in ECG Blog #340 (See Figure-3 in that post) — PVCs may sometimes show clearly abnormal ST elevation that is diagnostic of an acute MI. This is seen for the PVCs within the dotted RED ovals below in Figure-4.
- While not needed for diagnostic purposes in today's case (because the OMI is readily apparent from ST-T wave changes in sinus-conducted beats alone in Figure-4) — Awareness of PEARL #7 may prove invaluable for diagnosing acute OMI when no clear ST elevation is seen in sinus-conducted beats.
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| Figure-4: I've labeled key findings in the repeat ECG. |
CASE Conclusion:
- Cardiac cath was performed — and confirmed 100% LAD occlusion at a point just distal to the 1st Diagonal. The patient was doing well in follow-up.
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Acknowledgment: My appreciation to Edward Brunacci (from Sydney, Australia) 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 #228 — Reviews the concept of acute STEMI changes being seen in a PVC.
- ECG Blog #434 — Reviews a case involving assessment of the post-resuscitation ECG (ie, Which post-arrest patients need prompt cath?).
- ECG Blog #193 — Reviews the basics for predicting the "culprit" artery (as well as reviewing why the term "STEMI" should be replaced by "OMI" — which stands for an MI caused by acute coronary Occlusion).
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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.
- Recognizing ECG signs of Precordial Swirl (from acute OMI of LAD Septal Perforators) — See ECG Blog #380 — as well as 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).
This is a lovely tale, and the Story Teller is none other than Emeritus Professor Ken Grauer, the Number 1 ECG Guru in the world.
ReplyDeleteThank you so much for the support! — :)
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