The primary objective of the study is to evaluate the effect of 48 hours of intravenous (IV) omecamtiv mecarbil compared with placebo on dyspnea in subjects with left ventricular systolic dysfunction hospitalized for acute heart failure. This is a multicenter, randomized, double-blind, placebo-controlled study with 3 dose cohorts enrolled sequentially in order of ascending dose strength of omecamtiv mecarbil. In each cohort, subjects are randomized 1:1 to omecamtiv mecarbil or placebo.

This study was conducted by Amgen as the IND holder, with Cytokinetics as a collaborator. Due to the termination of the collaboration agreement between Amgen and Cytokinetics in May 2021 and subsequent transfer of the omecamtiv mecarbil IND from Amgen to Cytokinetics, Cytokinetics is now listed as the sponsor.

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