Friday, May 26, 2017

You're busy at triage and another ECG is flashed before your eyes.....

4 second video EKG from Stephen Smith on Vimeo.

Here is the computer read: 

You are working in triage where there are 30 patients vying for your attention and more coming in every minute.  The nursing assistant hands you an ECG every few minutes, wanting to know if the patient needs emergency placement.  She flashes the one above before your eyes.

What is your immediate impression?

The triage emergency physician saw the lateral T-wave inversions and told the assistant that there was no STEMI and to have the patient wait for the next available bed.

Here is the ECG again:
There is subtle ST Elevation in leads III and aVF, with reciprocal ST depression in aVL
This is diagnostic of inferior MI
There is very low voltage in the limb leads, so the ST segments are proportionally very abnormal.

There are also fairly well-formed Q-waves in II, III, and aVF, so this could be subacute or even possibly old (with persistent ST elevation -- aneurysm)

Case continued

The patient was placed in the ED on non-emergent basis.

Here is the history:

Patient has no previous cardiac history and presents to the ED with midsternal CP that radiates to the left and started 14 hours prior.  It was intermittent, but became constant 7 hours prior.  The patient also endorses SOB.   He denies N/V, fevers, chills or cough.  He smokes 5 cigarettes a day.  He states that it feels as if something is stuck in his chest when he swallows anything.

The faculty physician inside the ED had a better look at the ECG and immediately recognized the acute (subacute) inferior MI.

She activated the cath lab.

Another ECG was recorded 39 minutes after the first, before leaving for the cath lab:
There is some subtle evolution in V3-V6


1. Thrombotic occlusion of mid circumflex/second obtuse marginal with faint left to left collaterals
2. 70% stenosis of small First Diagonal
3. Diffuse 60-70% stenosis of the mid-RCA, but with TIMI III flow beyond

Here is the post-cath ECG:
The ST elevation in inferior leads is resolved.
T-wave inversion is deeper, consistent with reperfusion T-waves

Here is the troponin profile:

This is a very large MI.
Troponins have only modest correlation with infarct size because so much is dependent on reperfusion, but a Troponin I over 100 is very large.

The highest troponin I ever saw was 500 ng/mL in a case of left main occlusion.  That was BEFORE reperfusion,
The highest that my troponin research colleague, Fred Apple, has ever seen, is 1000!
A 4 month old with a cardiac arrest had an initial (and peak) troponin was 762 ng/mL!

Here is the formal contrast echo the next day:

Large inferolateral WMA
Decreased left ventricular systolic performance-moderate.
The estimated left ventricular ejection fraction is 35-40%.
Regional wall motion abnormality-anterolateral, akinetic.
Regional wall motion abnormality-inferolateral, akinetic.

Later, the triage physician told me about the case.  He said he was overwhelmed with patients at triage, pulled in many directions, and realizes he did not look at the entire ECG after seeing the T-wave inversions in lateral leads.  The obvious abnormalities stood out and distracted him from the more subtle ones.

Learning Points:

1.  Do not let the computer read fool you.  Do not even look at it until you have scrutinized the ECG.
2.  Don't let the obvious abnormalities prevent you from systematically scrutinizing the entire ECG.
3.  Large MIs often show only subtle (or no) ECG findings

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