Cardiac Resynchronization therapy with a defibrillator (CRTd) is a valid treatment for patients with heart failure and reduced left ventricle ejection fraction (HFrEF). Indeed, CRTd might induce an amelioration in New York Heart Association (NYHA) class, with a improvement of left ventricle ejection fraction (LVEF), and a reduction of hospital admissions for failing heart worsening. It is relevant to report that this ameliorative effect is seen only in a percentage about 70% of CRTd treated patients, that are called CRTd responders. However, about 30% of patients do not respond to CRTD, and they experience a worse clinical prognosis with an increasing trend toward heart failure (HF) disease progression, hospital admissions, and deaths. These patients are defined "CRTd non responders" . Actually, there is an increasing trend to find the mechanisms causing this therapeutic failure, such as a growing necessity to find new treatments to ameliorate CRTd effects, and to improve clinical outcomes in HFrEF patients with CRTd. In this setting, authors might speculate that salt and liquid retention represent a relevant pathogenic mechanism to cause worsening of NYHA class, with higher rate of hospital admissions for HF worsening and worse prognosis. Indeed, numerous studies reported the importance of a restricted vs. normal dietary salt intake in patients with HF to ameliorate clinical prognosis. Intriguingly, there are not studies investigating the effects of restricted dietary salt intake in failing heart patients with CRTd. Secondly, it is not well know how a restricted vs. normal dietary salt intake can affect clinical prognosis in CRTd patients. Therefore, the study hypothesis was that, a restricted dietary salt intake in addition to conventional anti-HF therapy as compared to the normal dietary salt intake in addition to conventional anti-HF drugs therapy might ameliorate heart function, and clinical outcomes in a population of HFrEF patients treated by CRT-d. Moreover, in this study authors will evaluate the effects of restricted vs. normal dietary salt intake in addition to conventional anti-HF in a population of failing heart patients treated by CRT-d. To date, in this study patients affected by HFrEF after CRT-d implant will be randomly divided in patients receiving restricted dietary salt intake plus conventional anti-HF therapy vs. patients under conventional dietary salt intake plus anti-HF therapy. In these patients authors will investigate at 12 months follow up all cause of deaths, cardiac deaths, hospitalizations for HF worsening, CRT-d responders rate, and the arrhythmic burden: atrial fibrillation (AF) events, ventricular tachycardia (VT) events, ventricular fibrillation (VF) events, internal cardioverter defibrillator (ICD) shocks, and strokes events.