ACS in presence of Bundle Branch Block (BBB) and Paced Ventricular Rhythm (PVR)

It’s a bit challenging to diagnose acute myocardial infarction (MI) with pre-existing bundle branch block (BBB) or paced rhythm.

Smith-Modified Sgarbossa Criteria is the most widely accepted ECG criteria for diagnosing acute MI in the presence of BBB or paced ventricular rhythm (PVR). It is created for more diagnostic accuracy based on rule of excessive discordance.

Smith-Modified Sgarbossa Criteria:

• Concordant ST elevation ≥ 1 mm in ≥ 1 lead
• Concordant ST depression ≥ 1 mm in ≥ 1 lead of V1-V3
• Proportionally excessive discordant STE in ≥ 1 lead anywhere with ≥ 1 mm STE, as defined by ≥ 25% of the depth of the preceding S-wave.

Learning Bite

Smith-Modified Sgarbossa Criteria is a very useful tool most widely accepted when it comes to ECG diagnosis of ACS with pre-existing BBB and VPR.