A Study to Learn More About How Safe Finerenone is, When it is Taken for a Longer Time With Standard Treatment, in Children and Young Adults With Heart Failure and Left Ventricular Systolic Dysfunction

Inclusion criteria

• For participants rolling over from randomized controlled trial (RCT): Prior participation in the finerenone Phase 3 study FIORE (21466) and not permanently discontinued from the study intervention prior to the end of treatment (EoT) visit in FIORE.
• For newly enrolled infants <6 months of age: Left ventricular systolic dysfunction (LVSD) with left ventricular ejection fraction (LVEF) ≤ 50% at screening assessed by echocardiography.
• For newly enrolled infants <6 months of age: Elevated NT-pro BNP levels (> 500 mg/L) at screening.
• For newly enrolled infants <6 months of age: Heart failure (HF) etiologies include congenital heart defects (CHD) with biventricular physiology and systemic LV; idiopathic cardiomyopathy (CM); familial/inherited and/or genetic CM; history of myocarditis (diagnosis of an acute episode at least 3 months prior to treatment assignment); neuromuscular disorder; inborn error of metabolism; mitochondrial disorder; acquired (chemotherapy, iatrogenic, infection, rheumatic, or nutritional); ischemic (e.g., Kawasaki disease and postoperative HF); LV noncompaction.
• For newly enrolled infants <6 months of age: Receiving standard of care (SoC) treatment for heart failure according to local guidelines or investigator´s discretion (on a stable regimen for 30 days before baseline).
• Newly enrolled newborns and infants < 6 months of age must have a body weight of ≥3 kg at Visit 1.

Exclusion criteria

• For participants rolling over from randomized controlled trial (RCT): To roll-over to FIORELLO, all participants: Potassium (K+) >5.5 mmol/L. After unblinding:

• For participants who received finerenone in FIORE: K+ >5.5 mmol/ L
• For participants who received placebo in FIORE: K+ >5.0 mmol/L for children ≥2 years of age, and >5.3 mmol/L for children <2 years of age (if eGFR is <60 mL/min/1.73m² for participants <2 years of age, the serum potassium threshold of >5.0 mmol/L will be used for exclusion)
• For newly enrolled newborns and infants < 6 months of age: Potassium ≥ 5.3 mmol/l (if eGFR is <60 mL/min/1.73m², the serum potassium threshold of >5.0 mmol/L will be used for exclusion).
• For participants rolling over from RCT: Severe renal dysfunction with estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73m² at FIORE EoT or Visit 1.
• For newly enrolled infants < 6 months of age: Severe renal dysfunction with eGFR < 30 ml/min/1.73m2 at screening or Visit 1.
• Treatment with a mineralocorticoid receptor antagonist, other than the study intervention, (e.g., spironolactone, eplerenone) within 30 days of Visit 1.
• Requirement of any intravenous (IV) vasoactive agents; mechanical ventilation; mechanical circulatory support; sustained or symptomatic arrhythmias not controlled by drug or device therapy within 30 days prior to study treatment.