• Has a clinical diagnosis of symptomatic heart failure (HF) ≥90 days prior to the Screening Visit;

• Is in New York Heart Association (NYHA) functional class II or III at the Screening Visit;

• Is on stable, guideline-directed therapy for HF, consistent with American Heart Association (AHA), American College of Cardiology (ACC), Heart Failure Society of America (HFSA) or European Society of Cardiology (ESC) guidelines for ≥4 weeks prior to the Screening Visit (with at least half of maximal labeled dose of renin-angiotensin-aldosterone system (RAAS) inhibitors and β-blockers, if tolerated);

• Has left ventricular ejection fraction (LVEF) ≤35% at the Screening Visit;

• Has a serum N-terminal pro b-type natriuretic peptide (NT-pro-BNP) level ≥600 pg/mL (or ≥900 pg/mL if the subject has atrial fibrillation or atrial flutter) at the Screening Visit.