## 4 Discussion  
The significant finding of the present subanalysis of our multicentre randomized controlled trial is that high adherence to the 9-week hybrid, comprehensive, cardiac telecrehabilitation results in a significant improvement of NYHA class, peak VO2, and it translates into a reduction in CV mortality and the composite endpoint of CV mortality or HF hospitalization in the long-term follow-up when the intervention was completed. In contrast to the partially and non-adherent group of patients, these favorable results were not observed. Additionally, our study showed that there are premises to believe that the 9-week intervention was sufficient to achieve high adherence in over 88% of patients who underwent HCTR, which might have resulted from both short-term improvement of physical capacity and long-term improvement of the prognosis. Moreover, these findings indirectly indicate that patients after the end of the intervention were able to implement healthy habits into everyday routine. It concerns patients' understanding of the necessity to follow both regular exercise training and daily pharmacological treatment as well as appropriate diet and promotion of mental health. The main analysis of the entire population of TELEREH-HF RCT demonstrated that a 9-week HCTR significantly improves the physical capacity and quality of life of HF patients in contrast with the usual care [17, 21]. Yet, it had no significant impact on mortality and rehospitalization rates in a long-term follow-up [17]. Only the subanalysis with the division into adherent patients versus partially and non-adherent patients proved that only adherent to HCTR patients achieved benefits in long-term follow-up in terms of prognosis and reducing hospitalization rates. It is in line with the World Health Organization statement that \"Increasing the effectiveness of adherence intervention may  
Figure 3: Kaplan–Meier probability of cardiovascular mortality or heart failure hospitalization in adherent patients vs. partially and non-adherent patients. have a far greater impact on the health of the population than any improvement in specific medical treatments\" [22]. There are only a few studies that were published that investigate the adherence to home-based telemonitored cardiac rehabilitation programs in HF patients. A single-center study randomly assigned 152 HF patients to an 8-week new model of home-based telemonitored rehabilitation or an outpatient-based standard rehabilitation. In line with our results, the adherence to telerehabilitation was high, and all patients completed cardiac telecrehabilitation program in contrast to standard rehabilitation, where the drop-out was 20% [13]. In another single-center trial, 111 HF patients were randomized in ratio 2:1 to a home-based telemonitored an 8-week Nordic walking training five times weekly or usual care. This study reported that 94.7% of the patients were adherent to telerehabilitation, only 5.3% of patients were partially adherent, and there were no non-adherent patients [14]. These results are consistent with our findings in terms of high adherence to the intervention. However, in our TELEREH-HF study, we noted 1.8% of non-adherent patients. Moreover, the results of published studies assessing the short-term effectiveness of telerehabilitation programs for HF patients are consistent and clearly indicated an improvement in both physical capacity and quality of life, which is a consequence of good adherence. Unfortunately, these two single-center studies did not assess the long-term impact of telerehabilitation on prognosis, unlike our multi-center trial [14; 15; 17]. However, the type of telemonitoring and the assessment of adherence were identical to those in our study [13; 14; 16; 17]. A small, non-randomized study by [PERSON] et al.