Implantable heart stimulating device comprising a left ventricular (LV) coronary sinus (CS) electrode lead at least provided with a tip electrode, a right ventricular (RV) electrode lead at least provided with a ring electrode, a pulse generating means connected to said leads and adapted to apply a stimulation pulse between said tip electrode and ring electrode, wherein the tip electrode being the cathode. The device comprises a monitoring means adapted to monitor for and detect anodal capture at said right ventricular ring electrode subsequent to a stimulation. If anodal capture at said right ventricular ring electrode is detected, at least one further electrode is arranged to function as indifferent electrode together with the ring electrode, in order to avoid anodal capture at the ring electrode.
