Saturday, November 22, 2014

Male in early 40's with 1.5 hours of chest pain

A third year medical student sent me this ECG and asked for my interpretation:

Recorded 0625
Here is what I wrote back: 
"Tough one.  Probably is acute LAD occlusion, needs serial ECGs/echo."
Standard ST elevation criteria

Note there is not enough ST elevation to meet the standard criteria, which require at least 2 mm ST elevation at the J-point, relative to the PQ jct., in leads V2 and V3 for a male over 40 years old.  In this case, there is 1 mm in V2 and 2 mm in V3.

1. Standardization and Interpretation of the Electrocardiogram, full text
2. MacFarlane 2004 (47% sensitive and 98% specific for MI as diagnosed by biomarkers.)


I had used my formula:

STEV350 = 2.5 mm (but it might be 3 mm)
QTc = 410
R amplitude in V4 = 14 mm

The value I obtained was 22.6 (23.2 if 3.0 mm is used for STE V3).

At a cutoff of 23.4 (my typically recommended cutoff), the sensitivity for LAD occlusion among subtle cases is 86% (much higher if all LAD occlusions are used as the denominator), with a specificity of 91%.

At a cutoff of 22.0, the sensitivity was 96% but with decreased specificity of 81%.

To me, the T-waves looked too fat to be normal.  And even though the formula was not greater than 23.4, at 22.6 or 23.2, it is close enough to be worried.

Outcome:

The pain had started at 5 AM, so that initial ECG above was at 1.5 hours after pain onset.

It was not recognized as possible LAD occlusion.  Initial troponin T was negative at less than 0.01 ng/mL (99% is less than 0.10 ng/mL).

2.5 hours later, the patient was seen by a cardiologist and the ECG interpretation was: "ECG - NSR without any ST-T changes.  No STEMI.  Will cycle markers and admit to Observation unit for rule out and stress test."

Comment: this is a patient who needs intensive evaluation in order to rule in, not rule out, MI

At 11:14, almost 5 hours after presentation and first ECG, the troponin T returned at 0.37 (this is pretty high for Trop T).   CK was 368.

A 2nd ECG was recorded:
All ST elevation has resolved, proving that the first ECG was indeed STEMI.  Fortunately for the patient, the LAD appears to have spontaneously reperfused.  There are persistent R-waves, suggesting that not too much damage was done.  But these can be misleading.

At 12:21 another ECG was recorded:
Now there is recurrent ST elevation.  The LAD is re-occluding.



The patient was taken for Cath at 1414 and was found to have a 100% proximal LAD occlusion after a large D1 (the D1 had a 90% stenosis).  So, mid-LAD occlusion.

Trop T at 1752 was 2.11 ng/mL (this is really quite high and indicates a large infarct and significant myocardial loss).

Learning points:

1.  Beware large fat T-waves.  Use the formula for differentiating normal variant ST elevation from subtle LAD occlusion.  A value less than 22.0 will only miss 4% of subtle LAD occlusion.  If the value is higher than 22.0, serial ECGs are essential.

2.  Cardiologists are not generally trained to find these subtle signs of coronary occlusion.

3.  This is a NonSTEMI due to coronary occlusion.  Many NonSTEMI are due to occlusion and do not get rapid reperfusion,  They are not diagnosed until late, when biomarkers return,  They usually do not go to the cath lab until the next day (because they are "NonSTEMI") and they thus have worse outcomes, higher biomarkers, and higher mortality than NonSTEMI who have an open artery at cath.

14 comments:

  1. A very subtle ECG !!
    I also noted some shallow inversion in III (and maybe avF) that makes me think that this is lateral STEMI when i was interpreting the ECG at first
    When i look back, i found out that T wave in V1 is maybe taller than V6 ? Does this make NTTV1 ?

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  2. hello doctor
    it's an interesting case in wich being proactive, instead of stubborn waiting for reaching arbitrary academic definitions, is really salutary.
    There's an upright T wave in V1 and it's greater than V6 in the First ECG , is that a reliable evidence for an impading LAD ?

    You're biggest from Algeria.

    ReplyDelete
    Replies
    1. Ben, good observation. See my comment above.
      Steve

      Delete
  3. Wow! - a truly humbling tracing. T waves on the initial ECG are "fatter" than they usually are - though if the history was of an asymptomatic young adult, then I would have called this normal. Given that the history was of a patient with chest pain - further evaluation is clearly indicated (ie, stat Echo; repeat ECG; close follow-up; serial troponin). An equally humbling tracing is the 2nd ECG - because it would be unimpressive - BUT in context that it is the 2nd ECG with the first showing peaked T waves - this 2nd ECG is diagnostic of an LAD that was occluded and has now spontaneously reperfused. LOTS of important lessons to be learned! - THANKS for posting - :)

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  4. I might have commented on the NTTV1, but I have only found that to be moderately useful. We did study that formally in our study and it added nothing to the logistic regression formula. On its own, as a univariate predictor, there was a significant difference: upright TW in V1 > V6 was presented in 35% of subtle LAD occlusion and 18% of early repol. Approximately. I'm going off memory now.
    But good observation, Ryan!
    Steve

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  5. Note: 1.ECG (Occlusion) - QTc 410 ms
    2.ECG (Reperfusion) - QTc 392 ms
    3.ECG (Re-Occlusion) - QTc 407 ms

    can serve ? thanks !
    Al



    ReplyDelete
    Replies
    1. Nice observation! But I think you got autocorrected to "can serve". Not sure what you meant.
      Steve

      Delete
  6. Hi Dr Smith,

    Firstly thanks for a great case, with some important learning points. I'm having a little trouble in the first ecg with STev3 here. Are we still going for 60ms after the j point and comparing it to the TP? I'm getting a value closer to 4mm which is skewing my formula result to 24.41.

    Any help here?

    Thanks

    Jim

    ReplyDelete
    Replies
    1. Jim,
      Good question. It is measured relative to the PQ jct. But, in this case, that is no different from using the TP segment. So I'm not sure how you're getting 4.0. I get between 2.5 and 3.0. Maybe you're not pinpointing the J-point accurately? If you do, then go 1.5 small boxes to the right and see where the tracing crosses that vertical line, it is 2.5 - 3.0 mm above the PQ jct.
      Steve

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    2. Dr Smith,

      Thanks very much for the quick reply. I think it was a problem with my phone as I've checked on my computer and it seems to be right now.

      Thanks again for the interesting case!

      Jim

      Delete
  7. Nice case. Do you think that the high troponine value from 17.52 , 4 hours after angioplasty, is indicative for STEMI type 4 a?

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  8. We know nothing about the final result of angioplasty, maybe the high troponine is caused by no-reflow, distal embolization etc, etc. Cath related STEMI (type 4a): If troponine is 5 times more than normal baseline value or troponine is with 20% more than anterior stable value..... Maybe the definition of STEMI type 4a is not the best...

    ReplyDelete
    Replies
    1. Follow up ECG proved good reflow. It was 100% occlusion with good reperfusion, but late.

      Delete

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