Wednesday, November 16, 2011

Anterior ST elevation: is it STEMI?

I received a call from an outside hospital.  A 31 year old healthy auto mechanic had a prolonged exposure to Carbon Monoxide in his garage and presented with blunted level of consciousness and chest pain.  There were others who were also affected.

I requested a transfer so that he could undergo immediate hyperbaric oxygen therapy at our hospital.  After the ambulance left the other hospital, the physician called to state that the patient was having an anterior STEMI with "tombstones."

The CO level returned at 14, so I knew that any STEMI would be due to simultaneous and incidental acute coronary thrombosis, NOT due to the CO toxicity.  I asked him to immediately fax the ECG, which is shown here:
What is it?











There is an R'-wave in V1 with downsloping ST elevation and an inverted T-wave.  There is ST elevation in lead V2.  This is not STEMI.  It is Brugada pattern

Brugada is frequently mistaken for STEMI, although it can also mask anterior STEMI.  I was not worried about this ECG.  When the patient arrived, his Brugada pattern had resolved: 


There is minimal STE and poor R-wave progression, but the QTc is 384, so this is early repolarization.  The Brugada pattern is gone.

We sent him to the chamber.  He was admitted to the hospital and ruled out for MI.  The patient's CO level was only 14, but he had had a prolonged exposure, had enough toxicity to cause objective neurologic deficits, and the blood level had been measured after prolonged oxygen therapy.

Brugada pattern ECG is not Brugada syndrome, which requires more than simply an ECG.  It is important to note that the pattern and the risk for cardiac arrest may not always be present, but may be induced by fever or sodium channel blocking drugs.  This makes me wonder if CO poisoning could induce or unmask Brugada pattern on the ECG.

Also, V2 makes this Brugada pattern atypical.

The patient should be referred to an electrophysiologist.

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