Which statement about torsades de pointes and QT interval is true?

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Multiple Choice

Which statement about torsades de pointes and QT interval is true?

Prolonged QT interval increases the risk of torsades de pointes because a longer repolarization phase creates a vulnerable window during which early afterdepolarizations can occur. These triggered impulses during late phase 2 to early phase 3 of the action potential can initiate a polymorphic ventricular tachycardia that twists around the baseline on the ECG. This is why many cases of torsades occur in settings that prolong the QT interval—such as certain drugs, electrolyte disturbances, or congenital long QT syndromes. While bradycardia can worsen QT prolongation and contribute to risk, the essential relationship is that a longer QT interval creates the substrate for torsades de pointes. Short QT intervals do not predispose to torsades.

Prolonged QT interval increases the risk of torsades de pointes because a longer repolarization phase creates a vulnerable window during which early afterdepolarizations can occur. These triggered impulses during late phase 2 to early phase 3 of the action potential can initiate a polymorphic ventricular tachycardia that twists around the baseline on the ECG. This is why many cases of torsades occur in settings that prolong the QT interval—such as certain drugs, electrolyte disturbances, or congenital long QT syndromes. While bradycardia can worsen QT prolongation and contribute to risk, the essential relationship is that a longer QT interval creates the substrate for torsades de pointes. Short QT intervals do not predispose to torsades.

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