Most chemotherapy protocols include serial assessment of the ECG, with particular emphasis on the corrected QT interval Avoidance of QT-prolonging medications and monitoring of electrolytes is essential with certain therapies to reduce likelihood of the development of potentially fatal ventricular arrhythmia such as torsades de pointes, especially in patients at risk for therapy-related diarrhea and emesis.16 Echocardiography Traditionally, studies of CTC in pediatric populations have been based on shortening fraction, and many chemotherapy protocols continue to include this as the sole marker to identify changes of concern More recently, EF has been incorporated but is not universally used There is no specified echocardiographic protocol included in COG guidelines, only that an “echocardiogram or comparable imaging should be performed to evaluate cardiac anatomy and function.” Guidelines are available for the multimodality imaging assessment of adult patients throughout cancer therapy, and the cardio-oncology echocardiogram protocol included can be used as a guide for pediatric patients.25 Included are two-dimensional (2D) and three-dimensional (3D) assessments of function, strain imaging, and measures of right ventricular function Both 3D EF and parameters of tissue deformation (strain and tissue Doppler) have demonstrated the ability to detect subclinical dysfunction in adult and pediatric studies.26–28 Despite this, the majority of current screening efforts in pediatric patients focus on standard echocardiographic measures and only in long-term survivors.29 One recent study did detail abnormal myocardial strain in a heterogeneous group of 25 pediatric patients immediately after their final treatment but did not include time points during treatment.30 Unfortunately, as opposed to studies in adults, those in children and adolescents have yet not proven the ability of changes in myocardial strain to predict later changes in symptomatic heart failure or even EF.26 Cardiac Magnetic Resonance Cardiac magnetic resonance (CMR) has increasing utility in detecting cancer treatment–related cardiotoxicity, particularly in patients with limited imaging windows and for assessment of the right ventricle One study of long-term survivors of pediatric cancers found abnormal left and right ventricular function (EF