Treatment of torsades de pointes in a patient on procainamide is which of the following?

• A. Intravenous Calcium
• B. Intravenous Magnesium
• C. Oral Potassium
• D. Subcutaneous Epinephrine

Answer: (B)

A life-threatening arrhythmia caused by a prolonged QT interval, such as when a QT-prolonging drug like procainamide is used, is best treated with intravenous magnesium sulfate. Magnesium stabilizes cardiac membranes and suppresses the early afterdepolarizations that drive torsades de pointes, making it the first-line therapy even if serum magnesium is normal. A typical approach is an IV magnesium sulfate bolus, with continuation as needed.

Calcium is not the go-to remedy for torsades and can be unhelpful unless there is true hypocalcemia. Replacing potassium helps if potassium is low, but it does not reliably terminate torsades on its own. Epinephrine would increase adrenergic stimulation and often worsen the arrhythmia. If magnesium fails, other strategies like temporary pacing or isoproterenol may be considered to increase heart rate and shorten the QT interval.