Carvedilol in Preventing Heart Failure in Childhood Cancer Survivors

Inclusion Criteria: * Males and females must weigh \>= 40 Kg * Patient must have had a cancer diagnosis \< 22 years of age, irrespective of current age * Patient must have a lifetime cumulative anthracycline dose of \>= 250 mg/m\^2 DOXOrubicin equivalent without the protection of dexrazoxane (Zinecard) therapy; the anthracycline dose threshold must be met as part of the treatment of a cancer that was diagnosed at \< 22 years of age * Note: Institutional records (e.g., clinic note, treatment summary, chemotherapy roadmap) can be used to document lifetime receipt of anthracycline dose * Patient must have completed cancer treatment \>= 2 years prior to study enrollment Exclusion Criteria: * Receiving treatment for cardiomyopathy or heart failure * Ejection fraction of \< 50% (by radionuclide angiogram or echocardiogram) or shortening fraction of \< 25% (by echocardiogram) * Note: for instances where both are reported, and one is below the threshold, the site will have the option to re-measure it centrally at the core lab * Uncorrected primary obstructive or severe regurgitative valvular disease: * Nondilated (restrictive); or * Hypertrophic cardiomyopathy; or * Significant systemic ventricular outflow obstruction * Sustained or symptomatic ventricular dysrhythmias uncontrolled with drug therapy or implantable device * Significant conduction defects (i.e. second or third degree atrio-ventricular block or sick sinus syndrome) * Bradycardia: heart rate \< 50 beats p…