The present study will create a registry of patients with pacemakers and ICDs who will undergo clinically indicated MRI and will document any adverse event or change in device parameters that may be associated with the imaging procedure. The results of this registry will provide the medical community with an accurate documentation of risk to patients and will establish a protocol of patient screening and device reprogramming for the purpose of maximizing the safe performance of MRI as a diagnostic tool in patients with implantable cardiac devices when indicated.