Moxifloxacin-induced QT prolongation and torsades: an uncommon effect of a common drug.

Torsade de pointes (TdP) or "twisting of the points" represents polymorphic ventricular tachycardia in the setting of prolonged QT interval and is characterized by QRS complexes that change in morphology and amplitude. We report a rare case of TdP, associated with QT interval prolongation, caused by intravenous moxifloxacin given for pneumonia in a 71-year-old African American man. Electrocardiogram initially revealed QT interval prolongation that led to torsades de pointes. These changes reverted to normal when moxifloxacin was held. Although the risk for quinolone-associated TdP seems to be low, caution is still warranted when given someone with high risk of QT prolongation.