This is a 3 month study for pediatric patients between the ages of 6 months and 18 years that have a current diagnosis of heart failure. This study will compare the use of the medication finerenone to placebo. During the study, participants will continue to receive their standard of care therapy according to pediatric heart failure guidelines. At the end of the 3 month study period, participants will have the option to enroll in a 9 month open label extension.

The FIORELLO study is for pediatric patients who 1) Have heart failure and left ventricular systolic dysfunction associated with dilated cardiomyopathy or congenital heart disease and 2) Have successfully completed the FIORE trial. Study participants will receive the study drug finerenone, which has not yet been FDA approved for this specific pediatric population. The study will last 9 months and the objective is to show that finerenone in addition to standard of care is safe when given long-term to pediatric patients with left ventricular systolic dysfunction.