Monday, June 6, 2011

Take a look at this prehospital ECG:

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A 49 year old woman with chest pain arrived.  The medics had recorded this ECG.  What is the diagnosis?

See explanation below




Let's go back in time 13 days:

A 49 yo woman with a h/o LAD stent, on aspirin and clopidogrel, complained of brief episodes of substernal pressure-like chest pain relieved by nitroglycerine.  She was seen in the ED on day 0 and was pain free in the ED.   She had had a previous anterior MI and had some baseline minimal wall motion abnormality.

Here is her ECG from 2 years prior:

It is normal except for some poor R-wave progression consistent with previous MI. 

Here is her ECG on the first day of presentation (day 0):

The T-wave in V1 is more upright and prominent, and there is subtle nonspecific ST segment depression in V5 and V6 (new).

Initial troponin I was less than 0.04 ng/ml (undetectable by the assay in use).  She was started on heparin, and was admitted to the hospital.  Her second troponin was 0.07 ng/ml (less than the 99th percentile of at least 0.10 ng/ml).  The third was again less than 0.04 ng/ml.  These troponins are below the diagnostic threshold for MI, but with such a rise and fall, even though below the diagnostic cutoff for MI, they suggest unstable angina, especially in the context of typical pain and h/o CAD.

The cardiologist decided to do an sestamibi stress test.  The first part of the test was done as an inpatient, but the patient was sent home with instructions to follow up for the second part of the scan.

Apparently she did not show up.


On day 13, this woman presented with chest pain.

And this brings us back to the ECG at the top.  It was recorded at t=0 on day 13, 15 minutes prior to ED arrival.
This is the same as the one at the top: There are hyperacute T-waves in V1-V4, ST elevation in V1 and V2, and ST depression in II, III, aVF, V5 and V6.  This is diagnostic of LAD occlusion
The physician did not know at the time that she had a previous ECG and a visit 13 days prior, but since the ECG is diagnostic, the cath lab was activated.

The cardiology fellow looked at the ECG and did not recognize MI, and wanted to deactivate the cath lab, but reconsidered after the following initial ED ECG was recorded.

This is obviously diagnostic of anterior STEMI
The patient had a 100% in stent thrombotic re-occlusion.  It was opened and stented.  Her initial troponin I was 0.07 ng/ml, and it peaked at 18 ng/ml because of a very fast door to balloon and symptom onset to balloon time.

3 comments:

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  2. thanks .. I tried to calculate the LAD formula I got qtc of (1.196X2)+(0.059X1.8)-(0.326X7) = 0.216 !!!

    i find it difficult

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  3. There is no computerized QTc and the baseline wanders, so it is difficult to come up with definite variables, but I plug in 400 for QTc, 1.5 for STE60V3 and 4.5 for RAV4 and the result is 23.9 (STEMI).

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