A joke I’ve heard a couple times in clinical medicine is that the definition of evidence-based medicine is the n of whatever a person saw last. This is the way that recency bias is often used in medicine. Essentially if we just saw something, say an aortic dissection, then we’re more likely to be looking for it going forward (for at least a time). Where does this fit in to this week’s EKG? Well, last week we had a pericarditis EKG with a decent distribution of up-coving ST elevation in a number of leads. I was wondering if that would sway this week’s quiz…
The RR intervals are about 4 big boxes wide so our rate is about 80. There look to be P’s before each QRS and QRS after each P so this is sinus rhythm. There looks to be a little bit of a left axis since we’re up in I but down in aVF. Along those lines, the P wave is inverted in V1 which may imply some Left atrial enlargement. The PR appears unremarkable. The QRS complexes appear narrow. Lead aVL starts drawing the eye, there looks to be a small q wave starting there.
Let’s talk about the ST segments. The J point is elevated in V4-V6 with about a millimeter of ST elevation. The shape of the T wave is fairly unremarkable, though a handful of you pointed out that the T waves look fairly tall possibly implying hyperacute T waves. Some people suggested repeating the EKG in short order (rarely a bad idea), but do we have more information about the lateral chest leads? Well, let’s look at the limb leads more closely.
Interestingly there’s a millimeter of ST elevation in II also (another reason I thought some people might call it pericarditis). aVL stands out. As mentioned before there’s already a q wave developing. The ST segment looks to be mildly elevated, but the shape is very concerning. In other sections of the EKG the STE is up-coving, here the ST segment is flattened and does not cove up. There’s also some reciprocal change suggested in III with a biphasic and initially down-sloping ST segment. Remember that aside from aVR and V1 that pericarditis will not have reciprocal changes.
The patient’s troponin turned out to be … 12. Not 0.12, not 1.2, but 12. That explains the q wave that’s likely to turn in to a Q wave in aVR (and probably I as well).
Take-homes from this EKG with Lateral STEMI? Injury patterns can be subtle, but respect ST elevation that does not cove up. The STE of pericarditis should always cove up and should not have reciprocal changes.