The ICONIC-M study is a multicenter randomized controlled study to assess patient response to CRT comparing ECGI map guided left ventricular lead placement with empirical lead placement. The hypothesis of the investigation is to demonstrate that CRT LV lead implantation guided by a map obtained with the Amycard 01C System and showing LV Latest Electrical Activated Site (LEAS) in combination with a CT cardiac venogram improves CRT outcome. An improved CRT outcome is defined as a ≥30% increase in LVESVi reduction compared to empiric CRT LV lead implantation. The sample size will be 136 in the Control arm and 194 in the Active arm. A total of 330 subjects. The study follows an adaptive design, in where one interim analysis at 70% enrollment will be performed. The sponsor may stop enrollment when either one of the following conditions apply: * Statistical significant difference between groups in the primary endpoint has been reached confirming a difference in reduction of the LVESVi of ≥30% in the Active arm compared to the Control arm * There is no trend or reason to believe statistical significance will be reached with a higher sample size. Statistical significance (primary endpoint) is reached at interim (70%) or at total (100%) of enrollment with a significance value P lower than 0.025.