Written by Pendell Meyers
Take a look at this ECG from a 57 yo M without any context first:
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What do you think? Imagine he presented with chest pain. |
There is normal sinus rhythm. QRS shows high voltage, likely representing LVH. There is STE in V1-V4 measuring up to 3-3.5 mm, and STD in V5-6. V2 has saddleback morphology, and V3 has a straight ST segment. V4 has slightly convex ST segment.
Findings that would potentially favor OMI: large absolute amount of STE, large proportion of STE to QRS in V1-2, STD in areas like V5-6 that would be considered reciprocal to V1-2 area, straight ST segment in V3 and slightly convex in V4.
Findings that would potentially not favor OMI: high voltage, LVH, saddleback morphology in V2, LVH with appropriate discordant ST/T segments explaining STE in right precordial leads and STD in left precordial leads. Saddleback morphology in V2, when in the same location as the STE that you are potentially worried about, is a quite strong feature suggesting a pseudoSTEMI pattern rather than true OMI.
In the proper clinical context, it would not be wrong to call this concerning for STEMI(+) OMI. But with more and more experience, some of these false positive features can be distinguished from true positives. Regardless, the first things to check would be the clinical context and any prior ECGs if available.
This ECG was sent to me without any context, and I responded, "I see why you are concerned, but I think this is likely a false positive from LVH. I would not activate the cath lab for this ECG at this point, but tell me more about the clinical picture and any prior ECG if available."
I sent it to Dr. Smith with no context, and he immediately responded: "very interesting pseudoSTEMI pattern"
In this case, the patient had only syncope which was explained by alcohol intoxication, poor PO intake otherwise, and standing in a line for a prolonged period of time. He did not have any active ACS symptoms.
Additionally, he was fortunate enough to go to an ED where they had his prior ECGs on file:
His troponin was less than 6 ng/L, and other basic labs within normal limits.
He had a prior echo on file showing symmetric LVH which was attributed to longstanding hypertension.
He had no family history of sudden death or obvious known HOCM, Brugada.
He was observed for sobriety and no further episodes of syncope or cardiac dysrhythmias were noted.
He was discharged.
See these examples of saddleback morphology in V2:
Saddleback ST Elevation. Is it STEMI? Is it type II Brugada?
Is this Saddleback a STEMI??
Is this STEMI? Pattern Recognition is Key
Anatomy of a Missed LAD Occlusion (classified as a NonSTEMI)
A Very Subtle LAD Occlusion....T-wave in V1??
See these other great and related posts about LVH:
Syncope, History of Coronary Disease, and ST Elevation: Should Medics Activate the Cath Lab?
Profound ST Elevation in V1-V3. What do you think?
A 31 year old with Diabetes and HTN complains of bilateral arm tingling and headache
Huge Anterior Voltage, with ST Elevation
Hyperacute T-waves? Anterior STEMI? No, LVH with PseudoSTEMI pattern!
Learning Points:
LVH causes some of the most common and most difficult ECG patterns to differentiate from STEMI and OMI.
When LVH causes pseudostemi patterns, the STE that catches everyones eyes is usually in the right precordial leads V1-V3, where it is discordant to the QRS of LVH.
Saddleback morphology, often in or around lead V2, is very uncommon in OMI of that same location, to the point that we have only been able to report 2 such cases (see links above), despite 1,326 (!) published as of today.
ST segment convexity and straightening are features that somewhat favor OMI, but this is most applicable in a normal QRS complex context.
Comparison to prior ECGs and the clinical context are obviously and always paramount, and can frequently help you out of false positive STEMI criteria scenarios like this.
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