Study to Evaluate the Safety and Efficacy of IV Infusion Treatment With Omecamtiv Mecarbil in Subjects With Left Ventricular Systolic Dysfunction Hospitalized for Acute Heart Failure (ATOMIC-AHF)

Inclusion Criteria: * Male or female 18 - 85 years * Hospitalized for worsening heart failure, within 24 hours of initiating IV loop diuretic * Dyspnea due to heart failure, at rest or with minimal exertion * History of left ventricular ejection fraction (LVEF) ≤ 40% * Elevated brain natriuretic peptide (BNP) or N-terminal fragment BNP (NT-proBNP) Exclusion Criteria: * Receiving IV vasopressor (excluding low dopamine), inotropic or mechanical support * Acute coronary syndrome (ACS) * Within 30 days prior to enrollment: cardiac resynchronization therapy (CRT) or implantable cardioverter defibrillator (ICD) implantation, ACS, coronary revascularization, transient ischemic attack (TIA) or stroke, sustained ventricular arrhythmia, or major surgery * Severe valvular stenosis, hypertrophic obstructive cardiomyopathy, active myocarditis, constrictive pericarditis, or clinically significant congenital heart disease * Estimated glomerular filtration rate (eGFR) \< 20 mL/min/1.73m2