Which of the following is the most likely associated laboratory abnormality in a patient suffering from arsenic poisoning?

Occupational exposure to arsenic may Occur in the smelting industry (due the presence of arsenic as a byproduct of purifying ores) and the microelectronics industry due to the use of gallium arsenate. Inorganic arsenic (currently used successfully and safely for the treatment of patients with acute promyelocytic leukemia) is more toxic than organic arsenic. Arsenic is rapidly cleared form the GI tract, kidneys, and lungs, where it originally resides, but leaves a long-term residue in the integument. Acute arsenic toxicity manifests as increased vascular permeability and intestinal inflammation. Cardiomyopathy may be seen with chronic exposure, with conduction system disease, including QRS widening, ST prolongation, and multifocal atrial tachycardia. Treatment of chronic poisoning should include chelation with dimercaprol.