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About Michelle Lin, MD

ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
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PV card: Early repolarization vs STEMI on ECG

You are handed an ECG for a 50 year old man with moderate chest pain for 2 hours now and no associated symptoms typical for ACS, PE, aortic dissection, or any other red flags of chest pain. He has no prior ECG’s on file.

  • Is this early repolarization or ST elevation MI?
  • Should I activate the cardiac catheterization lab?

Image courtesy of Dr. Steve Smith at HQMedEd-ecg.blogspot.com

Here are some great literature-based pearls compiled by Dr. Jason West (@JWestEM), an EM resident from Jacobi/Montefiore.

PV Card: ECG – Early Repolarization vs ST Elevation MI


Adapted from [1–7]
Go to ALiEM (PV) Cards for more resources.

Furthermore, there is a formula to differentiate early repolarization vs STEMI, per Dr. Smith’s publication6:

(1.196 x STE60V3) + (0.059 x QTc) – (0.326 x RA V4)

  • STE60V3 = STE elevation height at 60 msec (1.5 small boxes) after the J-point in lead V3 (mm)
  • QTc = The computer-read QTc interval
  • RA V4 = R wave amplitude in lead V4 (mm)

A result of > 23.4 is predictive of a LAD occlusion causing a STEMI, rather than early repolarization.

P.S. The above ECG image shows early repolarization.

References

  1. Brady W, Syverud S, Beagle C, et al. Electrocardiographic ST-segment elevation: the diagnosis of acute myocardial infarction by morphologic analysis of the ST segment. Acad Emerg Med. 2001;8(10):961-967. [PubMed]
  2. Brady W, Perron A, Syverud S, et al. Reciprocal ST segment depression: impact on the electrocardiographic diagnosis of ST segment elevation acute myocardial infarction. Am J Emerg Med. 2002;20(1):35-38. [PubMed]
  3. Smith S. Upwardly concave ST segment morphology is common in acute left anterior descending coronary occlusion. J Emerg Med. 2006;31(1):69-77. [PubMed]
  4. Larson D, Menssen K, Sharkey S, et al. “False-positive” cardiac catheterization laboratory activation among patients with suspected ST-segment elevation myocardial infarction. JAMA. 2007;298(23):2754-2760. [PubMed]
  5. Nfor T, Kostopoulos L, Hashim H, et al. Identifying false-positive ST-elevation myocardial infarction in emergency department patients. J Emerg Med. 2012;43(4):561-567. [PubMed]
  6. Smith S, Khalil A, Henry T, et al. Electrocardiographic differentiation of early repolarization from subtle anterior ST-segment elevation myocardial infarction. Ann Emerg Med. 2012;60(1):45-56.e2. [PubMed]
  7. Chung S, Lei M, Chen C, Hsu Y, Yang C. Characteristics and prognosis in patients with false-positive ST-elevation myocardial infarction in the ED. Am J Emerg Med. 2013;31(5):825-829. [PubMed]
By |2021-10-08T09:16:44-07:00May 16, 2013|ALiEM Cards, Cardiovascular, ECG|
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Trick of the Trade: Making the NG and NP procedures less painful

When doing nasogastric (NG) tubes and fiberoptic nasopharyngoscopy (NP) procedures, there many approaches in how patients can be locally anesthetized. Getting things pushed up your nose is so profoundly irritating that most patients only give you 1 or 2 changes to get it right.

One option is to use nebulized lidocaine, although it takes a while to prepare and anecdotally tends to numb mainly the hypopharynx, placing the patient at risk for aspiration later on. Another option is to use viscous lidocaine to coat the NG or NP tubing, but this is fairly messy and only mildly helpful. Commercial intranasal atomizers, which disperse lidocaine over the nasal mucosal surfaces well, are generally effective, but may not be available in some emergency departments.

By |2019-02-22T13:34:02-08:00Apr 23, 2013|Tricks of the Trade|
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Writing content for social media? Protect yourself!

Hand holding a Social Media 3d SphereIn the past few months, this blog has been successful in working with Google to remove pirating sites, which directly cut and paste all of our content (including PV cards!) directly into their own blog as their own. This broaches the greater question of disclaimers, copyright, and privacy.

Last month, Dr. Steve Carroll (EM Basic) nicely summarized these issues and constructed nice language for anyone’s social media productions. In fact, with his permission, I have incorporated much of the wordings into this blog’s disclaimer section (bottom of About Us). (more…)

By |2016-12-20T11:19:42-08:00Apr 7, 2013|Medical Education, Social Media & Tech|
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