Sgarbossa criteria for diagnosis of myocardial infarction (MI) in left bundle branch block (LBBB)

Criteria for Sgarbossa ECG algorithm

ST-segment deviation is measured at the J point. Concordance and discordance of ST segments are determined by comparison to the main direction of the QRS complex.

• the Sgarbossa algorithm is an effort to derive criteria to facilitate the diagnosis of acute myocardial infarction in patients with left bundle branch block
  • ECG findings from patients with left bundle branch block who were enrolled in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries trial (GUSTO-1) to those of a control group of patients with left bundle branch block derived from an outpatient ECG database (1)
    • using the presence of abnormal ST deviation at the J point to delineate 3 ECG criteria (herein termed the Sgarbossa ECG algorithm) (table above), the investigators derived and validated a scoring system for the prediction of acute myocardial infarction in the presence of left bundle branch block
      • a score greater than or equal to 3 had a positive likelihood ratio of 7.8 and a negative likelihood ratio of 0.2
• a meta-analysis evaluated Sgarbossa algorithm concluded (2)
  • a Sgarbossa ECG algorithm score of greater than or equal to 3, representing greater than or equal to 1 mm of concordant ST elevation or greater than or equal to 1 mm ST depression in leads V1 to V3, is useful for diagnosing acute myocardial infarction in patients who present with left bundle branch block on ECG
    • Sgbarvissa scores >= 3 have a low sensitivity and high specificity for predicting MI in bundle branch block
  • scoring system demonstrates good to excellent overall interobserver variability
  • a score of 2, representing 5 mm or more of discordant ST deviation, demonstrated ineffective positive likelihood ratios
  • a Sgarbossa ECG algorithm score of 0 is not useful in excluding acute myocardial infarction

Reference:

• 1. Sgarbossa EB et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators.: N Engl J Med. 1996 Feb 22;334(8):481-7.
• 2. Tobas JA et al. Electrocardiographic criteria for detecting acute myocardial infarction in patients with left bundle branch block: a meta-analysis. Ann Emerg Med. 2008 Oct;52(4):329-336.e1