Comparison of Cardiac Resynchronisation Therapy (CRT) Response Using High Frequency (HF) - ECG or Q-LV Guided Optimisation for Left Ventricular, Pacing Site.

Inclusion Criteria: * • Eligible for implantation of a CRT-D device according to published relevant ESC and CCS guidelines; * In sinus rhythm; * NYHA class II, III or IV * Have reviewed, signed and dated an informed consent. * Age 18 Exclusion Criteria: * Previous implant with a pacemaker, an ICD or a CRT device. (except upgrade from single chamber ICD with a fully functional defibrillation lead) not under recall or surveillance); * Persistent atrial arrhythmias (or cardioversion for atrial fibrillation) within the past month; * Ventricular tachyarrhythmia of transient or reversible causes such as acute myocardial infarction (MI), digitalis intoxication, drowning, electrocution, electrolyte imbalance, hypoxia or sepsis, uncorrected at the time of the enrolment; * Incessant ventricular tachyarrhythmia; * Unstable angina, or acute MI, Coronary Artery Bypass-Grafting (CABG), or Percutaneous Coronary Intervention (PCI) within the past 4 weeks; * Correctable valvular disease that is the primary cause of heart failure; * Indication for valve repair or replacement; * Recent Cerebro-Vascular Accident (CVA) or Transient Ischemic Attack (TIA) (within the previous 3 months); * On transplant waiting list; * Previous heart transplant; * Already included in another clinical study that could confound the results of this study; * Life expectancy less than 1 year; * Inability to understand the purpose of the study; * Unavailability for scheduled follow-up or refusal to cooperate; * Age of less than 18 years; * Pregnancy; * Drug addiction or abuse; * Under guardianship.