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Sgarbossa Criteria for MI in LBBB

Finds the STEMI hiding inside a left bundle branch block — positive rules in hard, negative rules out nothing.

Sgarbossa negative — rules nothing out
No criteria met
This does NOT rule out MI — original sensitivity is only 20–36%
Correlate clinically; apply Smith's ST/S ratio ≥0.25 before accepting a negative
0pts
Concordant ST elevation ≥1 mm in any lead with an upward QRS
Concordant ST depression ≥1 mm in V1, V2, or V3
Discordant ST elevation ≥5 mm in any lead with a downward QRS
Sgarbossa EB, et al. 1996 · Smith modification 2012 · Positive rules IN (98% specificity). Negative rules OUT nothing (original sensitivity 20–36%). Criteria 1 and 2 are each positive alone; criterion 3 is not. When criterion 3 is borderline, apply Smith's proportional rule (ST/S ratio ≥0.25) rather than the original 5 mm cutoff.