Tuesday, September 26, 2017

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.


6 comments:

  1. Got one question that I'm curious about, in one of your previous blogs you brought a case of Triple A, and mentioned how chest pain that is positional is not diagnostic of ACS... in this scenario, this patient had pain increasing with lying flat, which raised my initial suspicions as not ACS in nature..?

    ReplyDelete
    Replies
    1. Shanen,
      Chest pain that is positional is atypical for ACS, but ACS can be just about anything.
      This patient had only one factor that went against ACS: positional
      But he had many other that go for it: Age 50, diabetes, pain radiating to the left hand, dyspnea and diaphoresis, worse with exertion.
      Positional pain has a negative likelihood ratio of about 0.3, so decreases your suspicion, but definitely does not rule it out.
      This patient could easily have had another serious diagnosis or no serious diagnosis at all, but his EKG was dynamic and thus ACS. Troponin then positive.
      Steve Smith

      Delete
  2. Great case! RV4 can be low when there is clockwise rotation. My first impression is that this was normal ecg, except for clockwise rotation. The R wave progresses nicely but the transition is in V6. Of course, the other variables in the equation are not be changed. What are your thoughts about this?

    ReplyDelete
    Replies
    1. Dominic,
      That was my impression when I saw it, and I was surprised that the formulas were positive. But I was wrong about it. That is proven by how it normalizes with reperfusion.
      STeve

      Delete
  3. The thing that stood out to me as abnormal on the first ECG , concerning for LAD lesion, was the straightening of the ST segments in V2-V4, essentially a loss of ST segment with almost complete fusion of the ST segment and the T wave (Check mark sign as Mattu likes to call it).

    ReplyDelete

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