The purpose of the study is to evaluate the safety and efficacy of wearable defibrillator use in patients with left ventricular dysfunction or advanced heart failure symptoms, who have a high-risk for sudden cardiac death but are either not eligible for an implantable defibrillator under current guidelines or are not able to receive the device due to their condition.

Inclusion Criteria:

• Patients with NYHA class III or IV during the past month and one or more of the following:

  • hospitalization for cardiac decongestion and stabilization,
  • advanced heart failure receiving intravenous diuretics/inotropics in an outpatient clinic, or
  • awaiting cardiac transplantation

• Patients with left ventricular ejection fraction ≤ 35% and either one of the following:

  • coronary revascularization within 3 calendar months prior to enrollment, or
  • heart failure of non-ischemic origin diagnosed within 3 calendar months prior to enrollment.

• Patients awaiting ICD re-implantation following device explantation or lead extraction,

• Patients hospitalized with acute myocardial infarction and Killip Class III/IV.

Exclusion Criteria:

• The presence of an implantable cardioverter defibrillator prior to enrollment.
• Advanced cerebrovascular disease.
• Non-cardiac terminal illness associated with reduced likelihood of survival for the duration of the study.
• Use of supplemental oxygen in an outpatient setting requiring an external oxygen tank.
• Pregnancy.

patients with left ventricular dysfunction or advanced heart failure symptoms (New York Heart Association functional Class III/IV), who have a high-risk for sudden cardiac death, but are not eligible for an implantable defibrillator or are not able to receive one due to their condition.