Clinical Evaluation on Advanced Resynchronization

Inclusion Criteria: The patient candidate for inclusion in the study must be indicated for implantation of a Biventricular pacing system, with the following clinical conditions: * Severe Heart Failure (NYHA Class III or IV) * Cardiomyopathy of any etiology * Sinus rhythm * Reduced Left-Ventricular Ejection Fraction * Left-Ventricular End Diastolic Diameter greater than or equal to 30 mm/m2 (LVEDD\>30 mm/m2) * QRS Duration: * \> 150 ms or * \> 120 ms and documented Mechanical Dissynchrony (by ECHO) meeting two out of three of the following criteria: * Aortic Pre-Ejection Delay \> 140 ms * Interventricular Mechanical Delay \> 40 ms * Delayed activation of postero-lateral Left Ventricular wall (after mitral valve opening) * Optimal and stable (1 month before inclusion) pharmacological treatment, including, if tolerated, Beta Blockers, Angiotensin-Converting Enzyme (ACE) Inhibitors or ACE Inhibitor substitutes, Spironolactone, and diuretics Exclusion Criteria: Any patient who has one of the following characteristics will be excluded from the study: * ICD indication (Life-threatening ventricular arrhythmias) * Persistent or permanent Atrial Arrhythmia without possibility to restore sinus rhythm (spontaneous termination, anti-tachycardia pacing, pharmacological or electrical cardioversion). * Patient already implanted with a conventional pacemaker device * Myocardial infarction within the last three months * Heart surgery, or revascularization within the last three months, or expected * Heart surgery refused because of co-morbidity factors * Included in transplantation list * Already enrolled in other study * Life expectancy less than 1 year * Pregnancy * Age less than 18 * Forfeiture of freedom or under guardianship * Not able to understand the aim of the study and its procedures * Refusing to cooperate