Torsade de pointes. Asymptomatic patient on erythromycin had marked QT prolongation on ECG findings. Patient was profoundly hypomagnesemic and hypokalemic. This shows an example of recurrent nonsustained torsade de pointes that occurred several hours after the ECG was performed. With discontinuation of the erythromycin and aggressive repletion of the magnesium and potassium, no further torsade de pointes occurred and the patient's QT interval returned to normal