Here is the ECG of a previously healthy 35 year old male with one hour of chest pain:
There is obviously an inferior STEMI.
1. There is no reciprocal ST depression in lead I
2. There is ST elevation in leads V5 and V6.
3. ST elevation in lead II is at least as high as that in lead III
These are 3 criteria which are highly correlated with circumflex occlusion.
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Bairey CN et al. Am J Cardiol 1987;60:456
DeVerna et al. (including Kurz MC and Smith SW) has more recently developed a decision rule (see diagram), presented at ACEP Research Forum in 2008 [DeVerna CJ et al. Ann Emerg Med2008;52(4 Suppl):S117.]. We are in the process of validating this tool. A score greater than or equal to 5 diagnosed circumflex occlusion with very high specificity.