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LAD occlusion in the setting of paced rhythm

Posted Dec 22 2010 11:47am
An 80 yo male presented with chest pain.


There is clearly a ventricular paced rhythm. Normally in a paced rhythm, the QRS is all negative from V1-V6 because the pacing wire is in the apex of the RV and thus all depolarization goes away from the apex.
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In the above ECG, the QRS in V2 is positive and all others are negative, as in the patient's previous ECG below. This implies some problem with lead placement. Nevertheless, leads V1, V3, and V4 have excessively discordant ST segments.
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Though there is not a lot of data to support it, the ratio used for left bundle branch block seem to be applicable to paced rhythm. An ST/S ratio in V1-V4 > 0.20 is, I believe, quite specific for LAD occlusion. V2, though suspect because of the positive QRS, has a concordant ST segment, which is diagnostic of STEMI.

Previous ECG 2 months prior

The emergency physician needed to do some persuasion with the interventionalist, but succeeded and the patient was taken for angiography and PCI of a 100% LAD occlusion.

This is the ECG 2 days later


This is a much more difficult ECG because only complexes 4 and 5 are paced now. The precordial leads have an RBBB morpholoyg, with some minimal persistent ST elevation in v2 and V3 with T-wave inversion, suggestive of reperfusion.

Ischemic symptoms and a paced ECG with excessive discordance in V1-V4, with ST/S ratio > 0.20, is anterior STEMI until proven otherwise.
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