Heart failure, characterized by high mortality and morbidity rates, frequent hospital admissions, and prolonged stays in cardiology wards, significantly impacts patients' quality of life.

The REMOTI-HF is a single-center randomized controlled trial designed to assess the impact of remote monitoring, utilizing the HeartLogic and TriageHF algorithms, in patients with heart failure with implantable cardioverter defibrillator or cardiac resynchronization therapy. The primary endpoints include mortality, hospital admissions related to heart failure, and visits for worsening heart failure.

Moreover, we will explore the full capabilities of these algorithms, by analysing the association of physical activity, measured by the devices, with the same key outcomes. Additionally, the research will explore the relationship between the absolute values provided by the algorithms and NT-proBNP values.

Patients will be randomized into two arms: one with the activation of the algorithm and the other with no active algorithm. The algorithm is programmed to alert our team upon detecting a patient at risk of worsening heart failure. When an alarm is triggered, the patient will receive a telephone call from the investigation team. Subsequently, the patient may be scheduled for a hospital visit, or ambulatory medication adjustments can be made.

For patients in whom the algorithm is deactivated, no such alarm mechanism will be in place.

Patients in both arms will undergo comparison based on relevant heart failure events, defined as follows:

• All-Cause Mortality
• Hospital Admission for Heart Failure
• Hospital Visit for Worsening Heart Failure
• Ventricular Arrhythmias
• Atrial Arrhythmias

Additionally, the study will explore the association between physical activity measured by the devices and these specified events.

In addition to evaluating patient outcomes, a correlation analysis will be conducted to examine the relationship between the absolute value provided by the algorithm and absolute NT-proBNP values. This analysis aims to assess the concordance and potential predictive value of the algorithm's output with established biomarkers, specifically NT-proBNP, in the context of heart failure progression and severity (if possible).

Inclusion Criteria:

• Possession of an implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) device that is compatible with the HeartLogic or TriageHF algorithms.
• Left ventricular ejection fraction at the time of device implantation must be equal to or less than 35%.

Exclusion Criteria:

• Younger than 18 years old or older than 85 years old.
• Unable to be contacted when out of the hospital.
• Presence of severe cognitive impairment.
• Currently on the heart transplant waiting list

Patients will not know whether the algorithms was activated or not at the beginning of the study. However, if a contact with the patient is made due to the algorithm, the patient will then understand they are not on the control group.

The person responsible for contacts will also know if an individual patient is on the control or intervention group.