Arsenic trioxide is used in clinical trials in the treatment of relapsed an
d resistant cases of acute promyelocytic leukemia. Adverse effects from ars
enic in these studies have been multisystemic. Arsenic is known to cause co
rrected QT-interval prolongation and T-wave changes, but the potential for
serious ventricular arrhythmias is less well understood. Torsades de pointe
s, a form of ventricular tachycardia, has been reported with arsenic poison
ing but not at therapeutic doses used in protocols for hematologic malignan
cies. We describe 3 patients in whom this arrhythmia developed while they w
ere treated with arsenic trioxide. Early recognition of the arrhythmia or c
orrection of contributory factors is important because arsenic induced vent
ricular arrhythmias are known to be resistant to most chemical methods and
electrical cardioversion. (Blood, 2001; 97:1514-1516) (C) 2001 by The Ameri
can Society of Hematology.