Heart Sounds Registry

Inclusion Criteria: * Patients who are prescribed the WCD ≤ 10 days post-discharge after hospitalization with Heart Failure (HF), with and ischemic or non-ischemic cardiomyopathy. * Patients who have an ejection fraction (EF) ≤ 35% at the time of WCD prescription. * Patients are anticipated to wear the WCD for at least 3 months. * The subject must be 18 years of age or older on the day of screening. Exclusion Criteria: * Patients with pacemakers, an implanted cardioverter defibrillator (ICD), or a cardiac resynchronization therapy device. * Patients waiting for heart transplant. * Patients with known evidence of atrial fibrillation on their most recent ECG recording. * Patients currently hospitalized for acute myocardial infarction. * Patients with a planned revascularization within 30 days of screening. * Patients who are self-reporting to be pregnant. * Patients participating in another clinical study. * Patients not expected to live longer than 1 year. * For patients in the United States, those who are unable or unwilling to provide written informed consent in English. * For patients in Europe, those who are unable or unwilling to provide written informed consent in their country specific language or English.