This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to determine the relationship between cardiac function, exercise capacity, and cardiac rhythm to cardiac and liver iron loading. Eighty patients with various stages of iron overload will have a full, clinical cardiology evaluation (ECG, Echo, stress exercise and Holter monitoring) and a research MRI study (to quantify liver and myocardial iron and cardiac function). These studies may lead to 1) normative data for cardiac rhythm and performance for thalassemia patients, 2) determination of the prevalence of exercise and cardiac rhythm abnormalities in thalassemia patients with high cardiac iron and normal resting function, and 3) determination of the relationships between liver iron content, ferritin, cardiac T2* and cardiac function. These studies will provide the necessary groundwork for longitudinal studies of cardiac iron load on cardiac performance in thalassemia patients. The results of this study may lead to improved, early recognition of pre-clinical iron cardiomyopathy.