Sunday, April 15, 2012

Pseudonormalization of T-waves: STEMI

Here are other cases of pseudonormalization.

A 61 y.o. female with no h/o coronary disease presented with 3 days of nausea, vomiting, 3-4 liquid stools, and shortness of breath, especially with exertion. She denies fevers, chills, cough, chest pain, chest pressure, chest heaviness, diarrhea and abdominal pain. Her risk factors are HTN, smoking, and hyperlipidemia. 

Here is her initial ECG at 0508:
Sinus rhythm.  There are Q-waves in III and aVF diagnostic of old MI, and with the T-wave inversion in these leads, it appears to be fairly recent.  The inverted T-waves and relatively small Q-waves suggest that this was infarction was reperfused before it was complete.  T-wave inversion is often due to reperfusion and are thus sometimes called "reperfusion T-waves."  There is also ST depression in I, II, V4-V6 very suggestive of ischemia.

The Na returned at 117 mEq/L, but the troponin I returned at 8 ng/ml.   So the clinicians repeated the ECG at 0742:
There is now minimal ST elevation in III and aVF, and even more important, the T-waves have become upright in III and aVF, (although biphasic), with reciprocal ST segment and T-waves in I and aVL.  This is classic "pseudonormalization" of T-waves. 

Pseudonormalization of T-waves: "Normalization" because upright T-waves are usually normal, but "Pseudo" because even though they are upright, the fact that they are upright in this case is indicative of coronary occlusion.

She was moved to the critical care area, and at 0810, this ECG was recorded:
This is like the first one.  The involved artery has now reperfused, so the T-waves are inverted again ("reperfusion T-waves.")  so one would expect the artery to be open.  If this were a patient with chest pain, the pain would likely be resolved.  These T-waves are the analog to Wellens' T-waves which are described for the LAD or anterior wall.
The initial troponin I was 8 ng/ml, confirming that the infarct seen on the first ECG was recent.  The patient went for immediate PCI of a 95% distal RCA with hazy segment due to thrombosis.

Here is the ECG after PCI:

Not much changed from the previous.

Troponin I peaked at 18.  The inferior wall was akinetic on echo.

Learning points:

1.  Beware dyspnea in elderly women especially
2.  Subacute MI may present with T-wave inversion with or without Q-waves
3.  Subacute MI may have re-infarction
4.  If  T-waves of subacute MI turn upright (pseudonormalization), this is indicative of re-occlusion of the infarct-related artery

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