Torsades de Pointes is commonly associated with

• A. Short QT interval.
• B. Prolonged QT interval.
• C. No QT interval relation.
• D. No effect on QT interval.

Answer: (B)

Torsades de pointes occurs most often when the heart’s repolarization is prolonged, shown as a prolonged QT interval on the ECG. When the QT is long, tiny afterdepolarizations can appear during the late repolarization phase. These afterdepolarizations can trigger a rapid, twisting, polymorphic ventricular tachycardia that characterizes torsades de pointes and can deteriorate into more dangerous rhythms if not corrected. That’s why any situation or medication that lengthens the QT interval—electrolyte disturbances like low potassium or magnesium, bradycardia, and many drugs that prolong repolarization—raises the risk for torsades. Short QT, or no QT-related changes, does not carry the same TdP risk, so prolonged QT is the key association here.