In left bundle branch block, how are ST-T changes typically oriented relative to QRS polarity?

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Multiple Choice

In left bundle branch block, how are ST-T changes typically oriented relative to QRS polarity?

In left bundle branch block, ST-T changes are typically discordant with QRS polarity. This means the ST segment and T wave tend to go in the opposite direction to the main QRS deflection. If a lead shows a predominantly positive QRS, you’re likely to see ST segment depression and T-wave inversion in that same lead; if the QRS is predominantly negative, you’ll often see ST elevation and T-wave positivity. This pattern arises from secondary repolarization changes due to the abnormal depolarization sequence in LBBB, not from primary ischemic or other pathology. The other options don’t fit because ST-T changes do occur in LBBB, they are not concordant with the QRS, and they’re not limited to a single lead such as V1.

In left bundle branch block, ST-T changes are typically discordant with QRS polarity. This means the ST segment and T wave tend to go in the opposite direction to the main QRS deflection. If a lead shows a predominantly positive QRS, you’re likely to see ST segment depression and T-wave inversion in that same lead; if the QRS is predominantly negative, you’ll often see ST elevation and T-wave positivity. This pattern arises from secondary repolarization changes due to the abnormal depolarization sequence in LBBB, not from primary ischemic or other pathology. The other options don’t fit because ST-T changes do occur in LBBB, they are not concordant with the QRS, and they’re not limited to a single lead such as V1.

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