Heart transplantation is an advantageous procedure for selected patients with end-stage heart failure. Graft rejection remains a major factor limiting long-term survival despite continued advancement in the scientific skill of immunosuppression. Hyperacute rejection occurs rarely since screening of recipient for anti-donor antibodies was introduced. Focal or diffuse acute cellular rejection is diagnosed by endomyocardial biopsy (EMB). Coronary angiography (CA) is used to monitor for allograft arteriopathy, also described as chronic rejection. Repeated endomyocardial biopsy (EMB) remains the only surveillance method available. Endomyocardial biopsy is expensive, invasive, inconvenient to the patient, and associated with a significant incidence of serious complications. The MCG device is an invention that may provide a sensitive and objective means to assess alterations in the heart tissue. Because the acute inflammatory process of rejection deleteriously affects myocyte structure and function, we hypothesize that either or both the de- and re-polarization changes will occur in the cardiac cycle with subsequent changes in the cardiac magnetic fields and may give altered readings in the affected patient over time.