Sudden cardiac death is a tragic event that strikes all age groups and is unfortunately increasing in prevalence. Because it is difficult to predict those at highest risk, this study is designed to test the hypothesis that new imaging techniques (magnetic resonance imaging [MRI] and computed tomography [CT]) are useful for identifying factors which put people at high risk for sudden death.

Some people with heart disease and a weak heart muscle experience abnormal electrical activity of the heart that may predispose them to sudden death. In light of this risk, it has been recommended that such patients undergo implantation of an implantable cardioverter defibrillator (ICD). Your doctors have determined that you are such a patient and are to undergo implantation of an ICD. It is unclear who among the many patients who undergo ICD implantation for this reason are at greatest risk of sudden death and therefore require electrical response from their ICD. This research is being done to determine whether new imaging tests, such as magnetic resonance imaging (MRI) or multi-detector computed tomography (MDCT), can be used to predict who is at highest risk of sudden death and require electrical response from their ICD.

Inclusion Criteria:

• Left ventricular ejection fraction \

Patients with contractile dysfunction (EF< or = 35%) on an ischemic or non-ischemic basis undergoing clinically-indicated ICD implantation for primary prevention of sudden cardiac death (SCD)