211^At-BC8-B10 Before Donor Stem Cell Transplant in Treating Patients With High-Risk Acute Myeloid Leukemia, Acute Lymphoblastic Leukemia, Myelodysplastic Syndrome, or Mixed-Phenotype Acute Leukemia

Patients may not have symptomatic coronary artery disease and may not be on cardiac medications for anti-arrhythmic or inotropic effects

Left ventricular ejection fraction < 35%

Corrected diffusing capacity of the lungs for carbon monoxide (DLCO) < 35% or receiving supplemental continuous oxygen; when pulmonary function test (PFT)s cannot be obtained, the 6-minute walk test (6MWT, also known as exercise oximetry) will be used: Any patient with oxygen saturation on room air of < 89% during a 6MWT will be excluded

Liver abnormalities: fulminant liver failure, cirrhosis of the liver with evidence of portal hypertension, alcoholic hepatitis, esophageal varices, hepatic encephalopathy, uncorrectable hepatic synthetic dysfunction as evidenced by prolongation of the prothrombin time, ascites related to portal hypertension, bacterial or fungal liver abscess, biliary obstruction, chronic viral hepatitis, or symptomatic biliary disease