What is the acute treatment for torsades de pointes?

• A. Magnesium sulfate 1–2 g IV; correct underlying causes and monitor
• B. Lidocaine IV bolus
• C. Amiodarone IV
• D. Potassium chloride IV

Answer: (A)

Torsades de pointes is a QT interval–related polymorphic ventricular tachycardia, so the acute goal is to halt the arrhythmia and prevent recurrence by stabilizing the myocardium and correcting triggers. The best initial therapy is intravenous magnesium sulfate, given as a 1–2 g bolus. Magnesium works regardless of the serum level because it dampens the early afterdepolarizations that sustain torsades and helps normalize electrical stability of heart cells. If needed, you can repeat the dose or use a magnesium infusion while you address underlying factors like electrolyte abnormalities and removing QT-prolonging drugs.

Beyond magnesium, treat contributing issues such as correcting potassium to a high-normal range and eliminating drugs that prolong the QT. If the patient remains unstable or torsades recurs despite magnesium, synchronized cardioversion is performed. Lidocaine and amiodarone are not preferred here: lidocaine isn’t effective for torsades, and amiodarone can prolong QT and worsen the arrhythmia. Potassium replacement is important when needed, but magnesium is the key immediate antidote.