Drug-Induced Torsade de Pointes

A73-year-old man with mild coronary artery disease and a dilated cardiomyopathy presented to the emergency room with a hemodynamically stable wide-QRS tachycardia. His 12-lead ECG revealed episodes of ventriculoatrial block, and a diagnosis of ventricular tachycardia (VT) was made (Figure 1⇓). Intravenous procainamide restored sinus rhythm. Tachycardia recurred, and a second bolus of intravenous procainamide again restored sinus rhythm. The patient was started on concomitant amiodarone 800 mg/d.The next day, the patient had significant prolongation of the QT interval with prominent U waves (Figure 2 …