Arsenic trioxide can cause QTc interval prolongation and complete atrioventricular block. QTc prolongation can lead to ventricular arrhythmias that may be fatal.
QTc prolongation should be expected during treatment with arsenic trioxide. 16 of 40 patients (40%) with relapsed or refractory APML treated with arsenic trioxide had at least one QTc interval >500 msec on ECG tracing (from a total of 460 tracings taken).r
QTc prolongation was seen within 1 and 5 weeks following administration of arsenic trioxide, and returned to baseline by the end of 8 weeks following treatment.r
Use with caution in patients who have or may develop QTc interval prolongation i.e. patients with hypokalaemia, hypomagnesaemia, congenital long QT syndrome and patients taking medications that prolong QTc interval.