Reviewed October 2026. Left bundle branch block (LBBB) and right ventricular paced rhythms make conventional ST-elevation thresholds unreliable, but acute coronary occlusion may still be recognised. Use ECG criteria together with symptoms, prior ECGs, serial tracings, haemodynamic status and bedside imaging where indicated.
Original Sgarbossa criteria
- Concordant ST elevation ≥1 mm in any lead with a predominantly positive QRS complex (5 points).
- Concordant ST depression ≥1 mm in V1–V3 (3 points).
- Excessively discordant ST elevation ≥5 mm in a lead with a predominantly negative QRS complex (2 points).
A score ≥3 is relatively specific but insufficiently sensitive to exclude acute myocardial infarction when negative.
Smith-modified Sgarbossa criteria
The modified rule uses three unweighted criteria. It is positive if any one of the following is present:
- Concordant ST elevation ≥1 mm in a lead with predominantly positive QRS.
- Concordant ST depression ≥1 mm in V1–V3.
- Discordant ST elevation ≥1 mm with ST elevation / absolute S-wave depth ≥0.25 in a lead with predominantly negative QRS (equivalently, signed ST/S ratio ≤−0.25).
Example: 3 mm ST elevation with a 10 mm-deep S wave gives a ratio of 0.30 and meets the proportional criterion. The original absolute ≥5 mm rule is replaced, not added.
Interpretation and limitations
Modified criteria increase sensitivity for acute coronary occlusion compared with the original rule, but sensitivity and specificity vary between populations. A 2021 multicentre ventricular-paced-rhythm study reported sensitivity 81% and specificity 96% versus emergency department controls. Negative criteria do not rule out occlusion. With ongoing strongly suggestive ischaemic symptoms, urgent invasive assessment may still be indicated.
References: Smith et al., modified Sgarbossa rule; Dodd et al., paced rhythms; 2023 ESC ACS guidelines.
