Poison With a Purpose: A Case Report on Arsenic Cardiotoxicity and Obesity.

Acute promyelocytic leukemia (APL) is a form of leukemia in which there is an arrest of the maturation of the myeloid lineage at the promyelocyte stage. Although there is high early mortality due to coagulopathy, APL is now a curable disease with the use of arsenic trioxide (ATO) and all-trans-retinoic acid (ATRA). Arsenic is weight-based for the treatment of APL, and many toxicities are dose-dependent, although there are no guidelines regarding dosing adjustments for obese patients. We present a case of a 34-year-old male with obesity and APL who developed arsenic-induced QTc prolongation and symptomatic sinus tachycardia while receiving treatment. Further research is needed to guide appropriate dosing for obese patients to determine if ideal body weight dosing is able to provide similar cure rates with fewer adverse events.