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Author: Meaghan Mercer, DO
Emergency Medicine Resident
University of Nevada School of Medicine
AAEM/RSA President
I recently attended the #Resus14 conference in Las Vegas and Dr. Amal Mattu asked the audience how many felt comfortable with the Sgarbossa criteria. I was surprised at how few hands went up. Repetition is the key, but if you think you had Sgarbossa down there are some changes!
New LBBB is no longer a STEMI equivalent *UNLESS*
a. The patient has new heart failure
c. The EKG meets Sgarbossa A or B criteria
Quick review on Sgarbossa:
- Rule of discordance (normal): When the QRS primarily goes up then the ST segment should be a little bit below the baseline (think of leads I, II, III); when the QRS primarily goes down then the ST segment should be a little bit above the baseline (think of leads V1, V2, V3)
- Sgarbossa A: Concordant ST Elevation ≥ 1mm (in any lead)a. This means that the QRS complex and the ST segment are up in the same direction *IN ANY LEAD* (the QRS & ST are above baseline)
- Sgarbossa B: Concordant ST Depression ≥1mm in V1, V2, or V3 (*ONLY NEED ONE LEAD*)
- Sgarbossa C: is OUT! Discordant STE ≥5mm
New in the literature:
“Diagnosis of ST-Elevation Myocardial Infarction in the Presence of Left Bundle Branch Block With the ST-Elevation to S-Wave Ratio in a Modified Sgarbossa Rule.”
This is a 3-center trial where the investigators retrospectively reviewed all EKGs in patients with chest pain, symptoms of STEMI, and LBBB. The study group included 33 patients with evidence of occlusion on angiogram or a troponin >10 ng/mL within 24 hours. The control group consisted of 129 patients who did not have evidence of occlusion, had troponins which remained negative or under 10 ng/mL, and had an echocardiogram showing no wall motion abnormalities. For reference, Sgarbossa’s original study had a reference standard of CK with or without CKMB.
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What they found was that the ST to T ratio less than -0.25 improved diagnostic accuracy compared with the 5mm standard used in the original Sgarbossa C criteria. Dr. Smith’s ECG Blog explains it: A ratio of ST elevation at the J-point, relative to the PR interval (a positive number), divided by the preceding S-wave (a negative number, so the result is a negative number) that is less than or equal to -0.25, was far more sensitive and was more accurate than the Sgarbossa rule at diagnosing coronary occlusion.
The modified Sgarbossa criteria is being validated since the original study was underpowered, but it is looking very promising! We would love to hear if you have started using this modified Sgarbossa and its results.
TAKE HOME POINTS:
- New LBBB is no longer a STEMI equivalent *UNLESS*
a. The patient has new heart failure
b. The patient is unstable
c. The EKG Meets Sgarbossa A or B criteria - Sgarbossa C is out
- The modified Sgarbossa is promising but not validated yet. Keep your eyes out for new recommendations.
- Practice, practice, practice until this becomes second nature.
References:
Mattau, A. Modified Sgarbossa Rule. Dr. Mattu’s Emergency ECG Video of the Week website. http://ekgumem.tumblr.com/post/65979325231/modified-sgarbossa-rule-episode-114-november. Published November 4, 2013. Accessed March 31, 2014.
Smith SW, Dodd KW, Henry TD, et al. Diagnosis of ST-Elevation Myocardial Infarction in the Presence of Left Bundle Branch Block With the ST-Elevation to S-Wave Ratio in a Modified Sgarbossa Rule. Ann Emerg Med. 2012;60(6):766–776.
Smith, SW. Modified Sgarbossa Rule Published Online: Annals of Emergency Medicine. Dr. Smith’s ECG Blog. September 4, 2012. http://hqmeded-ecg.blogspot.com/2012/09/modified-sgarbossa-rule-published_4.html. Accessed March 31, 2014.
Lin, M. ALIEM MIA 2012: Smith SW et al. Diagnosis of ST-Elevation Myocardial Infarction in the Presence of Left Bundle Branch Block With the ST-Elevation to S-Wave Ratio in a Modified Sgarbossa Rule. Ann Emerg Med. 2012 Dec;60(6):766-76. Academic Life in Emergency Medicine website.
http://academiclifeinem.com/mia-2012-smith-st-elevation-myocardial-infarction-left-bundle-branch-block/. Published January 1, 2013. Accessed March 31, 2014.