Recent MI at another facility. Now back in the ER with chest pain

 Written by Willy Frick

A young woman with a history of paroxysmal nocturnal hemoglobinuria presented with acute substernal chest pain.

Five days prior, she had a similar presentation to a different hospital. She underwent coronary angiography which showed thrombotic occlusion of an RPL branch s/p aspiration thrombectomy. The report describes heavy plaque in the proximal RCA by IVUS, but no lesions in the previously occluded RPL branch and no stent was deployed. Her ECG afterward is shown below:

ECG from five days prior

Smith: this shows an old inferior MI with persistent ST elevation. It is consistent with an inferior LV aneurysm.  It is almost certainly not acute.

Queen: she saw no OMI (no "STEMI Equivalent") either

Continued:

Now, she says she was walking to the bathroom when she experienced acute onset substernal chest pressure radiating into her neck and left arm. She described it as the exact same sensation the she experienced five days prior.

What do you think?

Smith: All by itself, without any comparison with the previous, this ECG is diagnostic of acute inferior OMI.  One might suspect old MI (due to QS-waves in III and aVF), but the size of the T-wave in lead III (its total bulk) is too large for old MI.

The Queen of Hearts sees active OMI

Compared to the prior post cath ECG, we now see:

• STE and subtle Hyperacute T-wave in III

• New reciprocal STD and TWI in I/aVL

The primary changes are subtle, but especially with serial comparison, the reciprocal changes are unmistakably more active in the current tracing. Especially in this clinical context, the ECG is diagnostic for acute inferior OMI.

Smith: The cath lab should be activated now!

Presenting hsTnI was 385 ng/L (ref. < 35) and rose overnight to 4951. Documentation does not indicate whether she had persistent chest pain during this time. No repeat ECGs were obtained. She finally entered the cath lab 22 hours after her diagnostic ECG.

LAO cranial shot of the RCA

Here is an annotated still showing anatomy:

Dotted black lines indicate filling defects due to thrombus:

The cath report described mostly organized thrombus and heavy thrombotic burden. After aspiration thrombectomy, the patient received intracoronary alteplase without significant improvement in flow or thrombus burden. Throughout this process, the patient had repeated VF and was defibrillated 8 times.

Prolonged thrombectomy effort was unsuccessful. Post PCI angiogram is shown below.

LAO cranial shot of RCA post PCI

Unfortunately, there is still TIMI 1 flow. We do not know if thrombectomy would have been more successful 22 hours earlier when the patient first presented with OMI.

The patient's hsTnI peaked at 23,788 ng/L. Echo showed inferior and inferoseptal hypokinesis with preserved LVEF. The patient was started on eculizumab in an effort to reduce her thrombotic risk due to her paroxysmal nocturnal dyspnea.

This patient has a terrible disease to contend with (PNH). It would likely have been difficult to manage in the best of circumstances. But giving the thrombus a running start did not help matters.

Learning points:

• Differentiate old inferior infarct (ECG 1) from acute on chronic (ECG 2)

• Delaying time to angiography gives the thrombus time to organize

• Serial comparison in the setting of recurrent MI

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MY Comment, by KEN GRAUER, MD (11/26/2024):

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The KEY to today’s case lies with facilitating assessment of the current ECG from today’s patient (recorded at the time she presented to the ED) — by finding a comparison tracing. 

Take another LOOK in Figure-1 — which is the ECG that this patient now presents with. 

• This patient had been seen 5 days earlier at another hospital where she underwent aspiration thrombectomy for an acute event. She was discharged — but now presents to another ED with acute CP (Chest Pain) in association with this current ECG shown in Figure-1.

QUESTION:

• Why might it be EASY to overlook acute changes in ECG #2?

Figure-1: I've reproduced the current ECG in today's case. 

ANSWER:

If the current ECG (shown in Figure-1) was the only ECG you were given — it might be easy to overlook the acute changes because: — i) Nothing alarming is seen in the chest leads (with very small amplitude for the QRST complexes in leads V4-thru-V6); — ii) Large Q waves are seen in leads III and aVF (really QS complexes, which are fragmented in lead aVF). This is consistent with this patient's history of a recent infarction; — and, iii) The amount of ST elevation in leads III and aVF is limited. While there is some ST depression in leads I and aVL — it may be hard to know if this is "new" or "old".

• In short — While I would not from this single ECG be able to rule out the possibility of another acute event — this ECG in Figure-1 could be entirely consistent with this patient's prior event that occurred 5 days earlier.

How the Comparison Tracing Helps:

Finding a copy of this patient's last ECG (done 5 days earlier, at the time of her last hospital admission) — and placing it side-by-side to her current ECG (as we now do in Figure-2) — provides an immediate answer!

• Although subtle when viewed in isolation (as was done in Figure-1) — the ST elevation in leads III and aVF (RED arrows in Figure-2) — and the reciprocal ST depression in leads I and aVL (BLUE arrows) — is clearly new since ECG #1.
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• IMPRESSION: Although there is some change in QRS amplitude, frontal plane axis and R wave progression between the 2 tracings shown in Figure-2 — I did not feel this to be enough of a difference to alter the inescapable conclusion that leads III and aVF now show slight-but-real ST elevation — and leads I and aVL now show ST depression — that simply was not present 5 days earlier. Given the history of new CP in association with this patient’s current ECG — prompt cath is clearly indicated.

BOTTOM Line: Today’s case provides a superb example of how ready availability of a comparison tracing may sometimes provide an immediate answer regarding what is “new” vs “old” — vs “new superimposed on old”.

Figure-2: Comparison between the ECG from 5 days earlier — and today's ECG. (To improve visualization — I've digitized the original tracing for ECG #1 using PMcardio).