As requested by @jord7an, this covers Dr. Smith’s recent Annals publication regarding the differentiation of anterior STEMI from early repolarization abnormalities. Classically, early repolarization abnormalities manifest with prominent R waves, J-point elevation, ST-segment elevation, and a concave ST-segment morphology in the precordial leads. However, physician performance in practice at differentiating this pattern from true STEMI could be better, with benign repolarization making up about 10% of anterior STEMI cath lab activations.
In short, this is a retrospective evaluation of electrocardiographic features of anterior STEMI, trying to find an accurate, reliable rule to diagnose STEMI rather than a similar “pseudoinfarction” pattern. After doing objective measurements of several possible criteria between their comparison sets of “subtle” anterior STEMI and early repolarization, they come up with this rule:
(1.196 x STE60 V3) + (0.059 x QTc) – (0.326 x RA V4)
If the result of that equation is calculated as >23.4, there’s a +LR of 9.2 for STEMI, and a -LR of 0.1 if negative. And, those are useful LRs.
So, this is probably helpful. The authors suggest this could be easily programmed into the automatic rhythm analysis software of ECG machines, which is plausible. However, both the derivation and validation of this rule were performed retrospectively. The next step, ideally, would be a prospective comparison between rule-augmented clinical decision-making and non-augmented decision-making. Unfortunately, detecting small differences in clinical performance may require large samples, and these clinical dilemmas are not common at single centers.
“Electrocardiographic Differentiation of Early Repolarization From Subtle Anterior ST-Segment Elevation Myocardial Infarction”
www.ncbi.nlm.nih.gov/pubmed/22520989
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Great, thanks again. An issue some of my attendings had with the study during a presentation of it @ morning report was:
We do not know what the initial treatment or workup the "non cardiac chest pain early repol. got". We don't know if these were differentiated from STEMI, not getting cath etc. Its not so clear (or was not investigated retrospectively) in the methods. Therefore, somehow these early repol pt's seemed to somehow have been differentiated already by not getting cath??