Torsades de pointes due to QT prolongation: proper management?

• A. Calcium channel blocker
• B. Magnesium sulfate IV immediately; correct electrolytes; if still unstable, pacing or isoproterenol
• C. Observation
• D. Atropine

Answer: (B)

In torsades de pointes caused by QT prolongation, the priority is to rapidly stabilize the myocardium and suppress the trigger with magnesium and corrected electrolytes. IV magnesium sulfate is the first-line treatment because it helps prevent and terminate TdP by reducing early afterdepolarizations that drive the rhythm, even if serum magnesium isn’t low. Give magnesium right away and ensure electrolytes are optimized, bringing potassium into the upper end of the normal range while repleting magnesium if needed.

If the patient remains unstable, increasing the heart rate to shorten the QT interval is the next step, using temporary overdrive pacing or isoproterenol infusion. This approach reduces the pauses that can precipitate TdP and helps restore a stable rhythm.

Calcium channel blockers are not appropriate here because they can worsen conduction and don’t address the underlying mechanism. Simply observing isn’t adequate for a potentially life-threatening arrhythmia, and atropine targets bradycardia but doesn’t treat TdP itself.