Sgarbossa’s Criteria for MI in Left Bundle Branch Block

Formula

Pearls / Pitfalls

It's often difficult to identify an MI for patients with existing left bundle branch blocks (LBBB). About 1 in 200 patients with MI have LBBB. Sgarbossa's is a well accepted approach at determining which LBBB are having an MI.

Advice

A score of 3 or more is 90% specific for MI, but not sensitive (36%). Therefore a positive score should be acted upon, but a lower score can not by itself rule out MI - maintain a high index of suspicion if the presentation is consistent with MI.

More Information

As mentioned, Sgarbossa's criteria not rule out myocardial infarction in patients with pre-existing Left Bundle Branch Block (it is not sufficiently sensitive), but in patients with ≥3 points, it is specific for MI. Recently, Stephen Smith modified Sgarbossa Criteria looking at excessively discordant ST elevation and changing this slightly. This has been referenced by Dr. Sgarbossa herself (see reference) and should now be included in Sgarbossa criteria.