Interpretation
| Result | Meaning |
|---|---|
| Original ≥ 3 points | Acute MI likely (specificity ~90–98%) |
| Smith-modified ≥ 1 criterion | Acute occlusion MI likely (sens 91%, spec 90%) |
| Negative | Does not rule out MI |
Formula
Original: concordant STE ≥1 mm in any lead = 5 · concordant STD ≥1 mm in V1–V3 = 3 · discordant STE ≥5 mm = 2; positive if ≥3. Smith-modified (unweighted): concordant STE ≥1 mm, OR concordant STD ≥1 mm in V1–V3, OR discordant STE with ST/S ratio ≤ −0.25 (STE ≥25% of preceding S depth) in any lead; positive if ≥1.
Clinical pearls
- Measure ST deviation at the J point relative to the PR segment, and S (or R) amplitude to the nearest 0.5 mm.
- The original rule is specific but insensitive; a score <3 cannot exclude MI. The Smith modification raised sensitivity from ~52% to 91% at similar specificity.
- Concordant criteria apply equally to ventricular paced rhythms; hemodynamically unstable patients with LBBB and suspected ACS warrant emergent angiography regardless.
Examples
sgarbossa lbbb with concordant ste 1mm in v5modified sgarbossa st/s ratio -0.3 in v2, no concordant changesoriginal sgarbossa discordant ste 5mm only
FAQ
What are the modified Sgarbossa criteria?
Any of: concordant ST elevation ≥1 mm, concordant ST depression ≥1 mm in V1–V3, or discordant ST elevation ≥25% of the preceding S-wave depth (ST/S ≤ −0.25).
Is new LBBB a STEMI equivalent?
Not by itself any more; current guidelines use Sgarbossa-type criteria and clinical stability rather than LBBB alone.
Evidence
- Sgarbossa EB et al. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med 1996;334:481–7.
- 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;60:766–76.