Saturday, December 9, 2023

Syncope While Driving. Activate the Cath Lab?

A 50-something had syncope while driving. 

He was belted and it was low speed.  He had a prehospital ECG.  He was ambulatory at the scene.  He has a history of STEMI and heart failure.  The medics stated he had been nauseated and diaphoretic, but he did not have any chest pain or SOB. 

They recorded a prehospital ECG:

What do you think?

I read this blinded, with no clinical information, and read it as inferior OMI.  There is STE in inferior leads with a large T-wave and reciprocal ST depression in aVL with a reciprocally inverted T-wave.  It is all but diagnostic of OMI.  

The only alternative is old inferior MI with persistent ST-Elevation, or inferior aneurysm morphology Inferior Aneurysm morphology is incredibly hard to differentiate from Acute OMI, but you should suspect it whenever there are well-formed inferior Q-waves.  Unlike anterior aneurysm, a QS-wave is uncommon.   A QR-wave is far more common, just like you would see in inferior ACUTE OMI.   

And especially suspect Old MI when the patient gives a history of MI and has no chest pain or SOB.

The Queen of Hearts interprets it blinded also (no clinical information and no previous ECGs or serial ECGs).  This will be changed for future versions. 

The Queen of Hearts PM Cardio App is now available in the European Union (CE approved) the App Store and on Google Play.  For Americans, you need to wait for the FDA.  But in the meantime:


If you want this bot to help you make the early diagnosis of OMI and save your patient and his/her myocardium, you can sign up to get an early beta version of the bot here.  It is not yet available, but this is your way to get on the list.

Case continued

The conventional algorithm diagnosed ***STEMI*** and so did the paramedics.

The patient was given full dose aspirin and the medics activated the Cath Lab

What do you think about cath lab activation?

On arrival in the ED, the patient denied any symptoms at all. 

No chest pain, no shortness of breath, no back pain, no numbness, weakness, tingling, no seizures or history of seizures, 

First ED ECG
This still shows apparent inferior OMI.

The Queen agrees:

Because the patient had no symptoms, the diagnosis of OMI was doubted, and the providers were able to access a recent previous ECG:

Old ECG, most recent

Also appears to show inferior OMI, though because there is less STE, it appears to NOT be as acute as the above.

And then a slightly more remote past ECG

Old inferior MI

The patient's previous echocardiogram report was viewed:

Decreased LV systolic performance, estimated left ventricular ejection fraction is 35%.

Regional wall motion abnormality- inferior and inferolateral.

A Coronary angiogram from 8 years prior revealed that he had had an inferior posterior STEMI at the time due to 100% occlusion of the proximal RCA.

Here is the ECG from that visit:

Inferior-posterior-lateral OMI, already with well-formed Q-waves

And here is the post PCI next day ECG:

Q-waves persist
Notice the inverted reperfusion T-waves in inferior and lateral leads.
Notice the increased amplitude of the T-wave in V2 (posterior reperfusion)

The T-wave inversion will almost always normalize over weeks to months, leaving only the Q-waves behind.

And that is what we see in the presenting 2 ECGs at the top.

Case continued

The patient underwent an emergency formal echocardiogram and it was unchanged. 

Cath Lab activation was cancelled.

The patient ruled out by serial troponins.

Learning Points:

1.  When the patient has only syncope as a symptom, you should doubt the diagnosis of OMI, and seek other sources of information: Old ECGs, serial ECGs, Echocardiograms, angiogram reports.  

2.  The pretest probability of syncope without any other symptoms, for OMI, is low

3. Inferior aneurysm morphology is incredibly hard to differentiate from Acute OMI, but you should suspect it whenever there are well-formed inferior Q-waves.  Unlike anterior aneurysm, a QS-wave is uncommon.   A QR-wave is far more common, just like you would see in inferior ACUTE OMI.

4. Version 1 of the Queen of Hearts only sees one ECG out of context.  That will be improved in later versions!!


MY Comment, by KEN GRAUER, MD (12/9/2023):

Today’s case brings with it an important lesson — namely that the “right answer” (and the “right” clinical action) — will not always be correct. My 1st, 2nd and 3rd impressions of today’s initial ECG (which like Dr. Smith and QOH — I interpreted without benefit of any clinical information) — was, acute OMI until proven otherwise.
  • Acute OMI until proven otherwise is the "correct" answer — even though it turns out that this patient was not having an acute OMI.

  • This brings home a 2nd important lesson in today’s case — namely, that the History (both the past medical history — as well as the history of today’s presentation) — is an essential component of clinical ECG interpretation. Today’s patient has no CP (Chest Pain) — and once prior ECGs were discovered, it became apparent that as acute as today’s initial tracing may have seemed — the changes were not new!

The above said — I thought it may be insightful to review the initial pre-hospital ECG, which has to be interpreted as an acute OMI until proven otherwise.
  • Dr. Smith did prove otherwise — and so we all gain from this case the experience of how appearances can be deceiving.
  • BUT — the “correct” interpretation of this initial ECG remains, “Acute OMI until proven otherwise” — and IF this patient had with new-onset worrisome CP — strong consideration of prompt cardiac cath would be the "correct" action.

TAKE another LOOK at today’s initial tracing — that for clarity, I have digitalized and reproduced in Figure-1.

  • In addition to the large (wide) inferior lead Q waves + inferior ST elevation + reciprocal high-lateral lead ST-T wave depression (in leads I and aVL) — WHAT ELSE did I see that initially convinced me of an acute OMI until proven otherwise?

Figure-1: The initial ECG in today's case — obtained by the EMS team. (To improve visualization — I've digitized the original ECG using PMcardio).

Why ECG #1 Looks Acute ...
In addition to the acute-looking limb lead changes in Figure-1 — I've labeled several chest lead changes that convinced me that this tracing looks acute until proven otherwise. These include:
  • Especially the QRST complex in lead V3 (within the RED rectangle) — because of unmistakeable ST segment flattening (instead of the usual gental upsloping slight ST elevation normally seen in this lead) — in association with a disproportionately "hypervoluminous" T wave in this lead (that is "fatter"-at-its-peak and wider-at-its-base than expected given the size of the R wave in this lead).

By the concept of "neighboring leads" — given clear abnormalities in lead V3 — the ST-T waves in leads V2 and V4 are also abnormal.
  • Like lead V3 — the ST segment in lead V2 is normally slightly elevated and gently upsloping. Instead — the ST segment in lead V2 is isoelectric and unmistakeably flat (RED arrow in both leads V2,V3).
  • By itself — I would not necessarily interpret the ST-T wave in lead V4 as abnormal. But in the context of clearly abnormal leads V2 and V3 — the ST segment in lead V4 looks "straight", which results in accentuation of its intersection with the T wave in this lead. 

  • BOTTOM Line: In association with the acute-looking limb lead changes in Figure-1 — the above described findings (subtle-but-real) — increase my concern, and clearly suggest acute Infero-Postero OMI until proven otherwise.

"Take Home" Points from Today's Case:
  • The "right answer" (and the "right" clinical action) — will not always be correct. This is fine! The 1st STEP in clinical ECG interpretation is to assess the 12-lead ECG in front of you — and then to clinically correlate your impression.

  • The History is the essential 2nd STEP component of clinical ECG interpretation. So — despite our concern on seeing today's initial tracing — clinical interpretation of this ECG in the context of knowing the patient had no CP, and that prior ECGs were similar (from this patient's prior inferior MI) — provided us with a definite answer (and clear explanation for the abnormal initial ECG).


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