The Predictive Value of Dobutamine Echo-stress in the Clinical Response to CCM Therapy in Advanced HF

The goal of this observational cohort study, which is both retrospective and prospective, is to evaluate the long-term clinical and instrumental response to Cardiac Contractility Modulation (CCM) treatment in adult subjects suffering from symptomatic heart failure (HF) due to systolic left ventricular dysfunction, despite adequate medical therapy. Based on the response to stress echocardiography with preimplantation low-dose Dobutamine, the main questions it aims to answer are: * What is the proportion of subjects who experience a clinical response to CCM therapy at 12 months (NYHA reduction ≥ 1 class)? * There was a reduction in the number of hospitalizations, visits to the Emergency Department, and access to day hospital facilities for more than 4 hours compared to the year before the study (e.g., by intravenous infusion of cardiac inotropic drugs)? * What is the estimated change in the quality-of-life score using the "Quality of Life Questionnaire with Heart Failure - Minnesota" (MLHFQ) between baseline and the end of follow-up? * What is the change in walking distance between baseline and the end of the follow-up in the walk test (6MWT) (optional)? * What is the difference in NT-proBNP levels between baseline and the end of follow-up? Participants are already receiving CCM support as part of their regular medical care for heart failure.