N-Acetylprocainamide, Torsades de Pointes, and Hemodialysis

Excerpt

To the editor: N-acetylprocainamide (acecainide; NAPA) is the principal metabolite of procainamide. We report a case of N-acetylprocainamide-induced torsade de pointes that was resistant to overdrive pacing, but that responded dramatically to hemodialysis.

A 34-year-old woman with chronic glomerulonephritis had mitral valve replacement. Her admission electrocardiogram showed a QT of 0.35 seconds (QTc, 0.40). The blood urea nitrogen level was 65 mg/mL and the creatinine level was 2.6 mg/dL. On the fourth postoperative day, treatment was begun with procainamide for ventricular bigeminy. The ventricular bigeminy was suppressed at procainamide concentrations ranging from 2.7 to 5.6 µg/ mL for the next