Happy Turkey Day

We’ve all seen the patient who comes in complaining of chest pain with a left bundle branch block pattern (LBBB).  Many times we don’t have an old EKG to compare.  Just as a review, a LBBB presents difficulty since it will alter early and late ventricular depolarization to produce secondary ST-T segment changes.  Consequently, a LBBB makes it difficult to diagnose an acute MI.  The most commonly used criteria to help differentiate an Acute MI is the Sgarbossa Criteria from the GUSTO-1 trial.

The three ECG criteria with an independent value in the diagnosis of acute infarction and the score for each were:

  • ST segment elevation of 1 mm or more that was in the same direction (concordant) as the QRS complex in any lead — score 5.
  • ST segment depression of 1 mm or more in any lead from V1 to V3 — score 3.
  • ST segment elevation of 5 mm or more that was discordant with the QRS complex (ie, associated with a QS or rS complex) — score 2.

In a meta-analysis of the criteria done in 2008, presence of a score of 3 or above provided a specificity of 98%. It also showed a sensitivity of 20%.