An implantable cardioverter defibrillator (ICD) automatically determines whether to use electrogram (EGM) signals sensed by a true bipolar electrode pair or those sensed by an integrated bipolar electrode pair. EGM signals from both the true bipolar pair and the integrated bipolar pair are simultaneously sensed and compared to determine which pair produced more accurate sensing of cardiac events. The more accurate source of EGM signals is selected and used in determining the therapy to be delivered.