Three criteria are included in Sgarbossa’s criteria:
- ST elevation ≥1 mm in a lead with a positive QRS complex (i.e.: concordance) – 5 points
- concordant ST depression ≥1 mm in lead V1, V2, or V3 – 3 points
- ST elevation ≥5 mm in a lead with a negative (discordant) QRS complex – 2 points
≥3 points = 90% specificity of STEMI (sensitivity of 36%)
Modified Sgarbossa criteria
Modified Sgarbossa criteria were validated in 2015.
- The sensitivity of the modified criteria increases to 80% without affecting specificity.
- The third criteria regarding greater than 5 mm of discordance were chosen rather arbitrarily.
- The modified criteria change 5 mm to greater than 25% of the downward QRS deflection.
Criteria 3 is modified as follows: Discordant ST elevation greater than 25% of downward QRS deflection in a negative QRS complex (2 points)
Smith modified Sgarbossa rule:
- at least one lead with concordant STE (Sgarbossa criterion 1) or
- at least one lead of V1-V3 with concordant ST depression (Sgarbossa criterion 2) or
- proportionally excessively discordant ST elevation in V1-V4, as defined by an ST/S ratio of equal to or more than 0.20 and at least 2 mm of STE. (this replaces Sgarbossa criterion 3 which uses an absolute of 5mm)
Wackers et al. correlated ECG changes in LBBB with localization of the infarct by thallium scintigraphy. The most useful ECG criteria were:
- Serial ECG changes — 67 percent sensitivity
- ST segment elevation — 54 percent sensitivity
- Abnormal Q waves — 31 percent sensitivity
- Cabrera’s sign — 27 percent sensitivity, 47 percent for anteroseptal MI
- Initial positivity in V1 with a Q wave in V6 — 20 percent sensitivity but 100 percent specificity for anteroseptal MI