ASSURE WCD Clinical Evaluation - Detection and Safety Study

Inclusion Criteria: 1. Males or females, age ≥ 18 years 2. Patients with an active Implantable Cardioverter Defibrillator (ICD) 3. Left Ventricular Ejection Fraction (LVEF) ≤ 40%, measured within the past year (12 months) by echocardiography, nuclear imaging (including MRI), or left ventricular angiography 4. Able and willing to provide written informed consent before undergoing any study-related procedures Exclusion Criteria: 1. Any condition that by the judgement of the physician investigator precludes the subject's ability to comply with the study requirements, including cognitive and/or physical limitations that would prevent the subject from interacting with the device as intended 2. Any known skin allergy or sensitivity to the study garment materials that will be next to the skin 3. Any breached or compromised skin on the upper body that would be exacerbated by wearing the study garment 4. Work with or are frequently around equipment that produces high electromagnetic fields, for example magnetic resonance imaging devices, power supply facilities, or welding equipment 5. Any planned surgical or medical procedures during the participation period that would require the subject to remove the study device for more than 12 hours 6. Any planned air travel during the participation period 7. Pregnancy 8. Use of mechanical circulatory support, including but not limited to Left Ventricular Assist Device (LVAD) or Total Artificial Heart 9. Implanted Cardiac Resynchronization Therapy Defibrillator (CRT-D) 10. Simultaneous plan/prescription for Holter monitor, mobile cardiac outpatient telemetry (MCOT), Event Recorder, or in-hospital telemetry 11. Use of any electronic medical device that is worn on or near the body requires Sponsor approval, other than continuous positive airway pressure (CPAP), continuous blood glucose monitor, or pulse oximeter oxygen saturation (SpO2) monitor. 12. Under bust chest circumference greater than 52 inches or less than 28 inches 13. Current hospital inpatient