30 yo woman with chest pain and a "normal ECG" by the computer, this one prehospital

This was sent by paramedics in the Northwest Ambulance Service in the UK.  James Alameddine credits his partner, Gary Wilson.

Case

A 30 year old woman complained of chest pain and called 911.

She had a prehospital 12-lead ECG recorded:

As you can see, the computer interpretation is "normal"
What do you think?

This very perceptive medic noticed that the T-wave in V4 is far too tall for the QRS.  Very abnormal.  But computers are not programmed to find all abnormalities, including many that are dangerous.  This is this one.

How about ST Elevation?

There is (as the computer measures -- at the side) more than 1 mm of STE in V2 and V3, but not the 1.5 mm that would trigger "STEMI" in a woman.

Thus, you have to decide if this STE is due to normal variant or due to ischemia.  Normal Variant ST Elevation always has good R-wave progression, and here the R-wave in V4 is only 3 mm.

If we use the 3-variable formula, with STE60V3 = 2 mm, QTc = 413, and RAV4 = 3, the value returns at 25.8 which is clearly diagnostic of LAD occlusion.

The 4-variable formula which includes the QRS amplitude in V2 turns out to be: 20.6 (most accurate cutoff is 18.2), so both formulas predict LAD occlusion.

The T-waves in V4-V6 should never be taller than the R-wave and should even be far less tall.

They should look like this:

Here are some more examples of hyperacute T-waves in V4-V6:

An elderly man with severe chest pressure......

Ventricular Fibrillation, Resuscitation, and Hyperacute T-waves: What does the Angiogram show?

Chest pain in a 42 yo, relieved by Maalox and viscous lidocaine 

This one was also called "normal" by the computer (but in this case, also by the physician)


Case continued:

Because of this hyperacute T-wave, the medic continued to record serial ECGs over the next 20 minutes:

Now there is subtle ST depression in lead III, seen by the computer

Clear ST Elevation in I, aVL, V4-V6, with reciprocal ST depression in II, III, aVF

Obvious Proximal LAD occlusion

The medics activated the cath lab and the patient went straight to the cath lab and had an LAD occlusion opened and stented.

The medics were unable to get any other information such as troponins or echo.

Here are more cases of "normal" ECGs, posted on September 28:

Just a few cases that the computer called "normal"

Question: How would you like it if there was a policy that patients with "normal" ECGs do not need it to be reviewed by the physician?

This young woman with chest pain would be listed as "very low risk" and would sit in triage for many hours until she arrests or loses half of her myocardium.

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Just a few cases that the computer called "normal"

This article has been discussed on Twitter today.  

It purports to show that you don't need to read the ECG if the computer says "normal".  Many on Twitter seem to agree.

Safety of Computer Interpretation of Normal Triage Electrocardiograms

The confidence intervals were 97-100%.  Would you like to be 97% sure you're not missing an emergency?

So I just looked through a few of my blog cases that were read as "normal" by the computer.

Just as an aside: we are just finishing a manuscript studying a deep neural network EKG algorithm.

We compared the new deep neural network (DNN) from Cardiologs technologies(DNN) to Veritas conventional algorithm: Veritas: 364 "normal"; 5 missed emergencies. DNN: 493 normal; 2 missed.

So things will get better as technology advances.

We are not there yet.

Here are the cases:

Subtle Dynamic T-waves, Followed by LAD Occlusion and Arrest

How unreliable are computer algorithms in the Diagnosis of STEMI?

Chest Pain Diagnosed as Gastroesophageal Reflux

It is easy to be led astray by the computer....

This case which I posted on June 12 2017 in response to the article was not my case:

Should Emergency Physicians be interrupted by ECGs that are read as "Normal" by the computer?

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A 50-something with chest pain and minimal precordial ST elevation

A 50-something with diabetes presented with 3 hours of sharp chest pain radiating to the left hand, with dyspnea and diaphoresis; it was worse with exertion and with lying flat.

He had this second ECG, which was texted to me and I looked at it on my iPhone.  At the time of this ECG, the patient had received NTG and the pain was decreasing.

ECG-1:

There is 1 mm of ST elevation at the J-point in both V2 and V3 (within normal limits).
Computer interpretation is normal
Cardiologist overread is normal
What do you think?

More description: There is also poor R wave progression, with small R waves in V4. The T waves are slightly broad and large, but probably could not be called hyperacute. There is minimal STD in aVF.

One of our interns had texted this ECG-1 to me, with the message:

"3 hours of chest pain, QTc = 415 ms, 3 variable formula is 25.3.  What do you think?"

__________

[The 3-variable formula for differentiating normal variant ST elevation from the ST elevation of subtle LAD occlusion can be accessed by clicking on the link at the top of the page and entering the values into the online excel applet.  Values are: 1. ST elevation at 60 ms after the J-point in lead V3.  2. R-wave amplitude in V4. 3. computerized QTc.  See also the free iPhone app "SubtleSTEMI".  See also MDcalc.]

A value greater than 23.4 is very worrisome for LAD occlusion.

__________

I responded: 

"Not LAD occlusion.  What do you think?  Do the 4-variable formula."  (I just did not think it looked like an LAD occlusion)

I showed it to Pendell Meyers, and he said: To me it looks like it could be "on the way down" from LADO. The only way to prove it is with serial ECGs and the rest of the clinical story.   

Very perceptive.

__________

[The 4-variable formula adds the entire QRS amplitude in lead V2 and is more accurate than the 3-variable formula.  It is: (1.062 x STE at 60 ms after the J-point in V3 in mm) + (0.052 x computerized QTc) - (0.151 x QRSV2) - (0.268 x R-wave Amplitude in V4 in mm).  It can also be accessed at the top of the page, with value entry into the excel applet.]

The publication of the formula can be found here: A new 4-variable formula

A value greater than 18.2 is quite sensitive and specific for LAD occlusion. 

___________

The calculated value was 19.2

I suggested serial ECGs, which were done:

ECG-2: This one is about 50 minutes later:

Not much change

The first troponin I returned undetectable.

At about 3 hours after ECG-1, the second troponin I returned at 0.097 ng/mL.

At this time, the patient became pain free.

ECG-3. Here is the ECG in the pain free state:

Now there is less than 0.5 mm of ST Elevation.
Some people have nearly zero ST elevation at baseline.
For such patients, LAD occlusion may only manifest 1 mm of STE 

ECG-4. One hour later, this was his ECG (still pain free):

There is still only minimal STE.
T-waves in V2 and V3 are slightly less tall.
This suggests further resolution. 

ECG-5.  Later I discovered that there was an even earlier first ECG, recorded 50 minutes prior to ECG-1.

This has a lot of artifact.
It was called normal except for artifact.

But this is very interesting:
notice the T-wave in V2 is 8 mm, whereas it is 5 mm in the first ECG above.

As it turns out, the ECG at the top (ECG-1) was done after nitroglycerine, and the patient's pain had diminished "from 6/10 to 4/10." 

Here are all the V1-V3 leads, side by side:

                            1300               1350, pain decreasing               1430                  1700, pain free       1800, still pain free

This shows that the T-waves (which never were quite hyperacute), are deflating and may have been hyperacute prior to arrival.

Outcome:

The third troponin I, drawn 4.5 hours after presentation, returned at 4.2 ng/mL.

The patient went for angiogram and had an 80% mid-LAD thrombotic stenosis and proximal LAD disease, as well as a 90% diagonal lesion.  He went for Coronary bypass (CABG). 

This outcome is perfectly consistent with all the ECGs.

Learning points:

1. Pay attention to diminishing T-wave amplitude during diminishing pain.

2. The formulas are very accurate.  I have always thought that I can do better than my formulas, but now I'm in doubt.

3.  Some patients have near zero ST elevation at baseline. Any ST elevation in these patients is abnormal.  In such patients, LAD occlusion may result in very subtle ST elevation.

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