Unusual Effects of a QT-Prolonging Drug, Arsenic Trioxide, on Cardiac Potassium Currents

Abstract

As2O3 blocks both IKr and IKs at clinically relevant concentrations. On the other hand, it also activates IK-ATP, which maintains normal repolarization. We infer that variability in the extent of QT interval prolongation and onset of ventricular arrhythmias during arsenic therapy represents competing effects to block and activate multiple repolarizing potassium currents.