Prolonged QT interval increases risk for which lethal ventricular arrhythmia?

• A. Ventricular fibrillation
• B. Asystole
• C. Torsades de Pointes
• D. Atrial flutter

Answer: (C)

A prolonged QT interval means the ventricles take longer to repolarize. This delay raises the chance of early afterdepolarizations during late repolarization, which can trigger a rapid, irregular ventricular rhythm called torsades de pointes. Torsades is a dangerous, twisting polymorphic ventricular tachycardia that can deteriorate into ventricular fibrillation and sudden death if not treated promptly. While other lethal rhythms can occur, the link between a long QT and torsades de pointes is the classic relationship, whereas atrial flutter is a supraventricular rhythm and asystole is a non-paced, non-rhythm event not specifically caused by QT length.