EKG of the Week 2 – ANSWERS
Crazy case this week. Clinically, this guy looked terrible. We called a CODE STEMI on the patient after the second EKG given the fact that it was evolving. Cardiology came down to the ER and looked at the EKGs and agreed with us that given his clinical presentation and his EKGs, an emergent cath was warranted. They took him to the Cath lab and he had totally clean coronaries! Definitely wasn’t expecting that. Turns out, the EKG pattern we were seeing was just LVH with strain. I’ve attached a paper the Paul Basel (he saw the patient with me) sent me after the cath report came back. In case you don’t want to read the whole article, the main flowchart is attached to show you how the authors recommend trying to puzzle out STEMI vs LVH.
TAKE NOTE: The only way you can definitively prove the it is not a STEMI is in the cath lab. I would call a CODE STEMI on every single patient that presented like this with this EKG. Even the 4th year cards resident and attending thought this was a STEMI. I think it’s an interesting case, but remember, if in doubt, call a CODE STEMI. Better to be wrong, than miss a STEMI.
I drew out an example calculation of our EKG with V2 using their criteria to help you better see what the authors are trying to explain.
By their criteria, our case did not meet STEMI criteria.
In case you forgot the voltage criteria for LVH, they’re posted below (from life in the fast lane)
Limb Leads
- R wave in lead I
- + S wave in lead III > 25 mm
- R wave in aVL > 11 mm
- R wave in aVF > 20 mm
- S wave in aVR > 14 mm
Precordial Leads
- R wave in V4, V5 or V6 > 26 mm
- R wave in V5 or V6 plus S wave in V1 > 35 mm
- Largest R wave plus largest S wave in precordial leads > 45 mm
Link: Dr. Smith’s EKG Blog also does a bit on STEMI vs LVH
TAKE NOTE: Dr. Smith even talks about this paper in his blog: STEMI criteria in LVH
One retrospective analysis by Armstrong et al. suggested that, with LVH, STE in V1-V3 that exceeds 25% of the preceding QRS complex could be an accurate means for ruling out ACO, and fairly sensitive for identifying ACO.
Smith comment: The Armstrong paper did not have appropriate methods to study this. The appropriate methods would be to take consecutive ECGs with high voltage and ST elevation in the leads with ST elevation, separate them into those with and without LAD occlusion, and see what are the differences in ST/S ratio. I have inserted at the bottom of this post some examples from Armstrong’s paper. You will see that they are not cases that you would have difficulty with. I have tried to study this topic twice and failed because there are very few cases of high voltage in V1-V4 andLAD occlusion. In fact, even this case does not fit, as the voltage in the affected leads does not meet LVH criteria!
Most importantly, since STE in LVH rarely exceeds 4 mm in height, the 25% criterion is likely far too insensitive. For example, in a patient with an S-wave 30 mm in depth, the STE would have to exceed almost 7 mm.
It seems that the major conclusion of the sources I’ve read is: There is no great way to tell if it’s a STEMI or LVH with strain. If in doubt, call a CODE STEMI and have the cardiologist prove it in the cath lab!
Hope this week’s EKG got you thinking!