The purpose of this study is to verify whether optimizing the left ventricular lead position at implantation with the pacing cathode corresponding to the longest RV-to-LV electrical delay may result in a better patient outcome. The RV-to-LV electrical delay will be evaluated with RLD value (ms). RLD is the distance between the Right Ventricular pacing marker (VP) and the maximum peak (or the first maximum peak in case of two equally tall peaks) of the LV bipolar deflection.