An implantable cardiac lead comprises a lead body having a proximal end and a distal end, the proximal end of the lead body carrying a connector assembly connectable to an implantable medical device, and the distal end of the lead body carrying a distal electrode, a proximal electrode and an intermediate electrode positioned between the distal and proximal electrodes. Each combined ID is a combination of a target ID and one of Ma-index values. 5<Lo<Ls<2, thereby achieving the purpose.