23-07: Sgarbossa Criteria for AMI in Setting of LBBB

ECG Findings

• Concordant ST elevation ≥ 1 mm with a positive QRS complex (score = 5)

• Concordant ST depression ≥ 1 mm in leads V₁-V₃ (score = 3)

• Discordant ST elevation ≥ 5 mm (score = 2)

Pearls

1. Diagnosing STEMI in patients with left bundle branch block (LBBB) is challenging, because a normal LBBB produces ST-segment elevations and depressions that are typically used to diagnose STEMI. The Sgarbossa criteria can be used to diagnose acute MI (AMI) in the presence of LBBB with high specificity. However, most myocardial ischemia in the setting of LBBB does not produce these changes. An absence of these findings should not be used as evidence against acute coronary syndrome.

2. Score of greater than or equal to 3 gives a specificity for MI of 90%.

3. These criteria have been proposed to be used in patients with pacemakers as well. Small studies have demonstrated their utility in this setting, but larger studies are lacking. Nevertheless, the European Society of Cardiology guidelines have endorsed the use of the Sgarbossa criteria for catheterization lab activation in the setting of paced rhythms.

4. Modified Sgarbossa criteria have been proposed to increase diagnostic accuracy. In the modified criteria, the 3rd criterion (discordant elevation ≥ 5 mm) was replaced by discordant ST elevation with amplitude > 25% of the depth of the preceding S wave.