Which treatment is LEAST useful for torsades de pointes?

Which treatment is LEAST useful for torsades de pointes?

• A. Procainamide
• B. Magnesium
• C. Overdrive pacing
• D. Isoproterenol infusion

Answer: (A)

Torsades de pointes arises from a prolonged QT interval that promotes early afterdepolarizations and recurrent polymorphic VT. Treatments aim to shorten the QT and suppress those triggers, as well as address bradycardia or pauses. Magnesium is the first-line therapy because it stabilizes the myocardial cells and suppresses the EADs responsible for torsades, and it works even if magnesium levels are normal. Overdrive pacing and isoproterenol infusion both work by increasing heart rate, which shortens the QT interval and reduces the likelihood of pauses that trigger the arrhythmia. They are particularly useful when bradycardia or pauses contribute to torsades. Procainamide, on the other hand, prolongs repolarization and further lengthens the QT interval, which can worsen or precipitate torsades. In the setting of torsades, drugs that prolong QT are avoided, making procainamide the least useful option among the choices.

Torsades de pointes arises from a prolonged QT interval that promotes early afterdepolarizations and recurrent polymorphic VT. Treatments aim to shorten the QT and suppress those triggers, as well as address bradycardia or pauses.

Magnesium is the first-line therapy because it stabilizes the myocardial cells and suppresses the EADs responsible for torsades, and it works even if magnesium levels are normal. Overdrive pacing and isoproterenol infusion both work by increasing heart rate, which shortens the QT interval and reduces the likelihood of pauses that trigger the arrhythmia. They are particularly useful when bradycardia or pauses contribute to torsades.

Procainamide, on the other hand, prolongs repolarization and further lengthens the QT interval, which can worsen or precipitate torsades. In the setting of torsades, drugs that prolong QT are avoided, making procainamide the least useful option among the choices.