Wednesday, August 21, 2013

Chest Pain in a 61 year old male. Inferior STEMI without inferior ST elevation.

This 61 year old has a h/o CABG 20 years prior.  Onset of chest pain 1 hour prior to calling 911.  Here is the prehospital ECG:

Sinus rhythm.  There is an inverted T-wave in I and aVL, with very minimal ST depression, but no inferior ST elevation.  The T-wave in III does not have the normal amount of upward concavity.  There is a minmal right ventricular conduction delay (R' in V1). There is a biphasic T-wave in V2, and a quite large T-wave in V3 as well as inversion in V5
The only finding that is highly suspicious for ACS in this tracing is the ST segment and T-wave in aVL.  These two findings are early findings in inferior STEMI.

He arrived in the ED and had this ECG:

Now the findings in aVL are more pronounced, and the T-wave in lead III looks hyperacute, but still without ST elevation.  Also, there is ST elevation in V1, a common sign of right ventricular STEMI

A right sided ECG was obtained.  (V1-V6 are really V1R through V6R, on the right chest):

There is ST elevation throughout  the right sided leads (V2R-V6R).  There is still no ST elevation in inferior leads.  Only 0.5 mm is required for the diagnosis of RV MI, with reasonable sensitivity and specificity.  Here there is at least 1 mm in V2R through V4R)

The emergency physician activated the cath lab, and the interventionalist was not convinced but was persuaded to take the patient to the cath lab.

There was a 100% occluded proximal Right coronary artery.  It was opened and stented.

12 hour peak troponin I (for what that is worth) was 37 ng/ml.

Here is the post cath ECG:
Hyperacute T-waves have resolved.  Reciprocal ST depression is resolved.  There is still minimal ST elevation in V1, which may be the patient's baseline.  The T-waves in V2 and V3 have significantly changed.  I do not have enough details of the cath report and anatomy to explain these T-waves in V2 and V3; perhaps they are related to the right ventricular ischemia.


In our study of inferior MI vs. other etiologies inferior STEMI, 28% had ST depression and T-wave inversion in lead aVL before they had 1 mm of ST elevation in any inferior lead.  This case is especially unusual in that no amount of inferior ST elevation was present; the diagnosis relied upon reciprocal findings and right ventricular findings.

I don't have the whole cath  report, nor an echo showing  inferior wall motion abnormality.  One might argue that this was an RV MI only, without inferior wall involvement (a non-dominant RCA that only supplies the RV).  However, there are clearly inferior hyperacute T-waves which resolve, so this is an inferior wall MI.


  1. There seem to be Wellen's waves in present in the lateral precordial leads. Is it possible that the pt has a lesion in his LAD that is the cause of the anterior injury pattern 2nd to a "reverese coronary steal" phenomenom? Caused by blood being shunted from the proximal/mid-LAD to the distal-LAD to make up for the deficit from an occluded RCA?

    B/c it looks like areas supplied by the proximal RCA are more ischemic(e.g. the STE in R sided leads + the 2nd degree type II SA block + PR seg elevation in aVR and V1 possibly indicating an atrial infarction) than areas that are supplied by the distal RCA.

    1. Your thoughts are particulary plausible given that the patient has had a CABG. I don't know his anatomy, but it is conceivable that a graft could perfuse the distal RCA and not the proximal, and that there could be trouble with the graft to the LAD as well. I don't have the cath report.

  2. Dr. Smith,
    In the post cath ECG, there is now a biphasic T wave in aVL, however it is "down-up", rather than "up-down".

    Is this reciprocal to the reperfusion T wave you'd see (up-down) in the inferior leads? Although not visible in the inferior leads (much like the ST elevation was), can the reciprocal of reperfusion T waves be visible in aVL?


    1. Dave,
      Great observation. There are two reasons for a down-up T-wave: 1) reciprocal to reperfusion T-wave 2) the "up" portion is really a U-wave, think hypoK. This one in aVL is reciprocal to reperfusion in III.


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