A device for controlling the delivery of electrotherapeutic signals to a heart of a subject within a cardiac beat cycle, the device comprising: at least one electrotherapeutic signal delivering unit configured for being coupled to one or more ventricular electrodes for delivering one or more electrotherapeutic signals to said heart; a sensing unit operatively couplable to at least one of said one or more ventricular electrodes and to a distant electrode implanted in said subject, said sensing unit is configured for sensing at least one global intra-cardiac electrocardiac signal between a ventricular electrode and a distant electrode implanted in said subject, and for sensing at least one locally sensed electrical signal from said ventricular electrode; a processing unit operatively coupled to said at least one electrotherapeutic signal delivering unit and to said sensing unit, said processing unit is configured for controlling the operation of said electrotherapeutic signal delivering unit, for receiving from said sensing unit signals representing said global intra-cardiac electrocardiac signal and said locally sensed electrical signal; and a power source for providing power to said at least one electrotherapeutic unit, said sensing unit and said processing unit; characterized in that said processing unit is configured for processing said global electrocardiac signal and said locally sensed signal to detect a suspected ectopic electrical event within said cardiac beat cycle and distinguish between a ventricular ectopic electrical event and an electrical event originating from a supra-ventricular source; and for inhibiting the delivery of said electrotherapeutic signal to said heart upon detecting said ventricular ectopic electrical event. at least one electrotherapeutic signal delivering unit configured for being coupled to one or more ventricular electrodes for delivering one or more electrotherapeutic signals to said heart; a sensing unit operatively couplable to at least one of said one or more ventricular electrodes and to a distant electrode implanted in said subject, said sensing unit is configured for sensing at least one global intra-cardiac electrocardiac signal between a ventricular electrode and a distant electrode implanted in said subject, and for sensing at least one locally sensed electrical signal from said ventricular electrode; a processing unit operatively coupled to said at least one electrotherapeutic signal delivering unit and to said sensing unit, said processing unit is configured for controlling the operation of said electrotherapeutic signal delivering unit, for receiving from said sensing unit signals representing said global intra-cardiac electrocardiac signal and said locally sensed electrical signal; and a power source for providing power to said at least one electrotherapeutic unit, said sensing unit and said processing unit; characterized in that said processing unit is configured for processing said global electrocardiac signal and said locally sensed signal to detect a suspected ectopic electrical event within said cardiac beat cycle and distinguish between a ventricular ectopic electrical event and an electrical event originating from a supra-ventricular source; and for inhibiting the delivery of said electrotherapeutic signal to said heart upon detecting said ventricular ectopic electrical event.