[Plain language]: Heart failure (HF) patients often experience irregular heartbeats, known as arrhythmias. Atrial fibrillation (AF) is common among HF patients and can worsen their condition, leading to strokes and higher death rates. Most of what we know about arrhythmias in HF comes from patients with devices like ICDs or CRTs, which help manage heart rhythms. However, this study focuses on HF patients who don't qualify for these devices.

Researchers use the BIOMONITOR IV, a device that tracks heart activity remotely over a long period. The goal is to understand how often arrhythmias occur in these patients and to develop a predictive algorithm for worsening HF (WHF). This algorithm could help doctors intervene early and improve treatment, reducing hospital visits and deaths related to WHF.

To make the BIOMONITOR IV more effective for HF management, its firmware is updated to collect additional data, such as fluid levels, breathing rate, and body position. These factors may be important for predicting WHF events.

This study aims to collect clinical data with regard to the two main study objectives:

- Objective arrhythmia: Assess the incidence of arrhythmias and the contribution of the BIOMONITOR to arrhythmia diagnosis and subsequent treatment.

- Objective heart failure events: Collect data from BIOMONITOR sensors and relate them to the heart failure status for development of a predictive algorithm for worsening HF.

Inclusion Criteria:

• Patient has diagnosed heart failure for ≥90 days and current symptoms compatible with NYHA class II-III (according to most recent assessment)
• At least ONE of the following:

At least one documented admission with a primary diagnosis of worsening heart failure within last 12 months prior to enrollment;

OR Unscheduled outpatient visit with increase of oral loop diuretics (more than 2-fold) or IV diuretic or ultrafiltration therapy for acute WHF within last 6 months prior to enrollment;

OR elevated NT-proBNP/BNP values within last 3 months prior to enrollment i.e.:

If LVEF >50% --> Patients in SR: >450 / >150 pg/ml; Patients with AF present: >900 / >300 pg/ml

If LVEF <50% --> Patients in SR: >900 / >300 pg/ml; Patients with AF present: >1800 / >450 pg/ml

• Ability to understand the nature of the study
• Willingness to provide written informed consent
• Ability and willingness to perform follow-up visits at the study site and via phone
• Ability and willingness to use the CardioMessenger and acceptance of the BIOTRONIK Home Monitoring concept

Exclusion Criteria:

• Implanted with pacemaker, ICD or CRT device or ICM
• Class I indication for a pacemaker, ICD or CRT according to current guidelines.
• Permanent or long-standing persistent AF
• Stroke, MI or PCI/CABG within 3 months prior to enrollment
• Patient is on chronic renal or peritoneal dialysis
• Patient has complex adult congenital heart disease
• Patient has active cancer involving chemotherapy, immunotherapy or radiation therapy
• Patient life expectancy is less than 1 year
• Age <18 years
• Patient is participating in any other device or drug trial that may interfere with the treatment or protocol of this study or may significantly affect the study outcomes

Anonymized data may be shared with qualified healthcare practitioners or academic researchers upon request and with permission of BIOTRONIK. Requests shall be sent to the Clinical Research Department of BIOTRONIK.

To be specified

See above

Only commercial features of the BIOMONITOR IV are open label. The additional sensor data recorded by the study software are blinded to investigators and participants.