An implantable stimulation lead is disclosed for placement in the coronary sinus region and its associated coronary vessels overlying the left side of a patient's heart. The lead comprises at least one proximal connector; at least one tissue stimulation electrode; at least one conductor coupled between the at least one proximal connector and the at least one stimulation electrode; and a lead body including a housing of insulating material enclosing the at least one conductor, the lead body having a relatively flexible distal portion of, for example, silicone rubber, having a length corresponding to the coronary sinus region of the heart, and a stiffer proximal portion of, for example, polyurethane. A robust transition joint comprising telescoped sections of the distal and proximal portions of the lead body couples the two portions of the lead body.
Also provided is a versatile lead delivery system including a stylet stop disposed within the distal portion of the lead body. The stylet stop defines an aperture dimensioned to pass a guide wire but not the enlarged distal tip of a stylet. The lead includes a tip electrode having a longitudinally extending bore dimensioned to permit passage of the guide wire through the tip electrode.