An endocardial lead for stimulation of the left ventricle, comprising: - a lead body with an insulated flexible hollow sheath, including a central lumen accommodating an inner conductor axially and rotationally mobile within the lumen; - on the proximal side, an electric connector for the coupling to a generator of an active implantable medical device, this connector including at least one central pin linked to the inner conductor; - on the distal side, a lead head with a tubular body fastened to the sheath and continued on the distal side by a protruding anchoring helical screw, fastened to the lead body, the lead head being adapted to extend in the cavity of the right ventricle and the anchoring screw being adapted to penetrate in the right wall of the interventricular septum under the effect of a screwing movement imparted to the sheath of the lead body from the proximal end of the lead; - a stimulation needle electrically connected to the inner conductor and comprising at its distal end an active free part with at least one stimulation electrode adapted to apply stimulation pulses, this needle being a telescopic needle axially mobile between a retracted position, inside the tubular body, and a fully or partially extended position, with the active free part of the needle emerging out of the tubular body, the lead being characterized in that, so as to allow an intraseptal stimulation by the needle, where said pulses are applied to the septum in a neighbouring region of the left wall of the latter, the lead further comprises: - an operating mechanism (62, 64, 66) adapted to produce a controlled displacement of the needle, from its retracted position to its partially or fully extended position, under the effect of a movement of relative rotation of the connector pin with respect to the lead body, such movement being imparted to this pin from the proximal end of the lead, this operating mechanism comprising: - a guiding and driving core rotationally and translationally fastened to the needle, and translationally and rotationally mobile inside the tubular body; and - means (64, 66) for coupling the core to the tubular body, adapted to transform a movement of relative rotation of the core with respect to the tubular body into a movement of axial translation of the core inside the tubular body. - a lead body with an insulated flexible hollow sheath, including a central lumen accommodating an inner conductor axially and rotationally mobile within the lumen; - on the proximal side, an electric connector for the coupling to a generator of an active implantable medical device, this connector including at least one central pin linked to the inner conductor; - on the distal side, a lead head with a tubular body fastened to the sheath and continued on the distal side by a protruding anchoring helical screw, fastened to the lead body, the lead head being adapted to extend in the cavity of the right ventricle and the anchoring screw being adapted to penetrate in the right wall of the interventricular septum under the effect of a screwing movement imparted to the sheath of the lead body from the proximal end of the lead; - a stimulation needle electrically connected to the inner conductor and comprising at its distal end an active free part with at least one stimulation electrode adapted to apply stimulation pulses, this needle being a telescopic needle axially mobile between a retracted position, inside the tubular body, and a fully or partially extended position, with the active free part of the needle emerging out of the tubular body, - an operating mechanism (62, 64, 66) adapted to produce a controlled displacement of the needle, from its retracted position to its partially or fully extended position, under the effect of a movement of relative rotation of the connector pin with respect to the lead body, such movement being imparted to this pin from the proximal end of the lead, - a guiding and driving core rotationally and translationally fastened to the needle, and translationally and rotationally mobile inside the tubular body; and - means (64, 66) for coupling the core to the tubular body, adapted to transform a movement of relative rotation of the core with respect to the tubular body into a movement of axial translation of the core inside the tubular body.