## 1 Introduction  
Heart failure (HF) can be effectively prevented and treated. There is a need to implement the knowledge acquired through large randomized clinical trials, included in the procedures standards, into everyday practice.  
Adherence to treatment recommendations in HF patients is of major prognostic importance; however, thorough implementation of guidelines in routine care remains insufficient [1; 2].  
In the current European and American guidelines for the management of HF, cardiac rehabilitation is a class 1 recommendation, level of evidence A [3; 4]. Moreover, it is recommended to create and develop a multidisciplinary management program for HF patients. It should be done by incorporating both clinic-based and home-based strategies combined with patient engagement and self-evaluations [4; 5; 6; 7].  
Despite beneficial effects in improvements in functional capacity, quality of life, outcomes, cost-effectiveness, and strong recommendations, cardiac rehabilitation remains underused [1; 5]. According to the recent EUROASPIRE V registry, less than half of patients (46%) were advised to participate in a cardiac rehabilitation program, and 69% of those advised attended less than half of the sessions [8].  
There may be several factors for poor adherence to cardiac rehabilitation [9]. Starting from the lack of resources and logistical problems (e.g., transportations issues, a lack of caregivers) and ending with patient-related reasons such as disability, helplessness, and psychological problems (e.g., the low motivation of the patients themselves, depression, anxiety) [1]. Despite the progress in pharmacological and non-pharmacogical treatment of HF, the effects achieved are not always optimal. An important factor determining results after the treatment or the introduction of a new therapeutic procedure is patients' adherence, which can affect their prognosis [10; 11; 12]. Therefore, both in the assessment of pharmacological treatment as well as in the evaluation of new procedures, it is advisable to evaluate them also in terms of their adherence.  
Little is known about adherence to home-based remote supervised exercise training. To date, only a few papers assessed short-term adherence to telerabilitation programs in HF patients. There are no published data that evaluate both the short-term adherence to telerabilitation and its impact on long-term prognosis (when the intervention was completed) in HF patients depending on their good or poor adherence [13; 14].  
The development of new telemedicine technologies made it possible to introduce a program of telerabilitation that might be an option to overcome barriers hindering the implementation of cardiac rehabilitation in everyday clinical practice [1; 6; 7; 9; 10; 11; 12; 15].  
It is worth emphasizing that the recent scientific statement from the International Society for Holter and Noninvasive Electrocardiology/Heart Rhythm Society/European Heart Rhythm Association/Asia Pacific Heart Rhythm Society indicates the hybrid cardiac telecrehabilitation as a novel promising approach [11]. Moreover, joint expert opinion by the Polish Cardiac Society and the Polish Academy of Science considers the comprehensive hybrid cardiac telecrehabilitation as a procedure equivalent to the conventional inpatient and/or outpatient rehabilitation (class I) [12].  
Therefore, we aimed to investigate the association of adherence to hybrid comprehensive telem rehabilitation (HCTR) with mortality and hospitalization in the long-term follow-up, i.e., 14-26 months after the intervention was completed based on data from Telerehabilitation in Heart Failure Patients TELEREH-HF Randomized Clinical Trial.