Sgarbossa criteria

The diagnosis of new left bundle branch block (LBBB) or ventricular pacing (VP) and chest pain implies acute myocardial ischemia or infarction.
However, interpretation of repolarization in LBBB and VP can be challenging.

The (modified) Scarbossa criteria help to differentiate signs of acute ischemia in the ECG, which can be seen equivalent to myocardial infarction with ST elevation (STEMI).

There are 3 original criteria for myocardial ischemia in patients with lbbb:

1. ST elevation > 1mm in one of the leads with positive QRS complex concordant to the R wave (5 points)
2. ST depression > 1mm in one of the leads V1 - V3 concordant to the S wave (3 points)
3. ST elevation >5mm discordant to the S wave (1 point)

A score of 3 or more is reported to be 90% specific for myocardial ischemia. However, sensitivity is low.

Stephen Smith modified the Sgarbossa criteria to improce sensitivity. Because the cutoff of 5mm for discordant ST elevation (#3) was arbitrary, he proposed a relative ST elevation more than 25% of the preceding S wave amplitude.

Both other criteria (#1 and #2) remained unchanged.

If you want to read more about ecg criteria of LBBB, click here

You want more insights?

1. Smith SW, Dodd KW, Henry TD, Dvorak DM, Pearce LA. Diagnosis of ST Elevation Myocardial Infarction in the Presence of Left Bundle Branch Block using the ST Elevation to S-Wave Ratio in a Modified Sgarbossa Rule. Annals of Emergency Medicine 2012;60:766-76.
2. Sgarbossa EB, Pinski SL, Barbagelata A, Underwood DA, Gates KB, Topol EJ. Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. N Engl J Med 1996;334:481-7.
3. Cai Q, Mehta N, Sgarbossa EB, et al. The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: From falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time? Am Heart J 2013;166:409-13.