Conventional defibrillators are manually operated defibrillators that have to be attached to the patient and operated by a healthcare provider or layperson. In contrast, the purpose of AECDs is to automatically detect life-threatening arrhythmias and deliver external shocks according to a programmable prescription for hospitalized patients, who may be at transient risk for the development of life-threatening arrhythmias. AECDs immediately and automatically monitor, detect and treat cardiac arrhythmias with no human intervention. The AECD proposed to be utilized in this trial, PowerHeart CRM, a product of Cardiac Science, Inc, has been evaluated in the hospital setting to assess safety and efficacy, and has been approved by the FDA to be prophylactically attached to hospital patients and provide automatic defibrillation therapy without human intervention.