The Persistence of Autoantibody Neutralisation by BC 007 in Patients With Chronic HFrEF and Autoantibodies Against the Beta1-Adrenergic Receptor

Primary objective is: \- To compare the efficacy of an intravenous (i.v.) infusion of BC 007 with an untreated control arm in removal of β1 AAb at month 12 in participants with chronic heart failure with reduced ejection fraction (HFrEF) Secondary objectives are: * To evaluate the time to recurrence of β1 AAb after a single i.v. infusion of BC 007 * To evaluate the response rate and time to recurrence of β1 AAb after a repeated single i.v. infusion of BC 007 after the first recurrence of β1 AAb * To evaluate the safety and tolerability of BC 007 after a single and a repeated single i.v. infusion * To determine the pharmacokinetic (PK) plasma and urine profiles of BC 007 * To investigate the PK plasma profiles of BC 007 metabolites * To investigate the β aminoisobutyric acid (β-AIBA) plasma and urine, and uric acid serum and urine concentration as a marker for BC 007 degradation * To investigate the spontaneous conversion of β1 AAb status from positive to negative in untreated participants (control arm) Exploratory objective is: \- To evaluate the change of the left ventricular ejection fraction (LVEF) after a single and a repeated single i.v. infusion