A cardiac resynchronization therapy system, comprising: an implantable lead system (120, 130) comprising left and right ventricular electrodes (134, 134', 134", 134"', 654a, 654b, 654c, 654d, 655, 126, 656) configurable in at least an extended bipolar configuration and at least an alternative bipolar or unipolar configuration differing from the extended bipolar configuration, at least one left ventricular electrode (134, 134', 134", 134"', 654a, 654b, 654c, 654d, 655) defining a cathode of the extended bipolar configuration and a right ventricular electrode (126, 656) defining an anode of the extended bipolar configuration; energy delivery circuitry (730, 735) coupled to the lead system; sensing circuitry coupled to the lead system; a controller coupled to the sensing circuitry and the energy delivery circuitry, the controller configured to execute program instructions for sensing cardiac electrical activity and delivering cardiac resynchronization therapy to the heart in accordance with programmed pacing parameters including a non-zero intraventricular delay, the controller configured to deliver a pace pulse to the at least one left ventricular electrode defining the cathode of the extended bipolar configuration; and characterized by a detector coupled to the sensing circuitry and the controller, the detector configured to sense for a response to the pace pulse and detect anodal stimulation of the right ventricle based on the sensed response; and the controller is configured to selectably switch from a current extended bipolar pace vector to an alternative bipolar or unipolar pace vector without ganging an additional anode electrode with the right ventricular electrode to mitigate or eliminate detected anodal stimulation of the right ventricle. an implantable lead system (120, 130) comprising left and right ventricular electrodes (134, 134', 134", 134"', 654a, 654b, 654c, 654d, 655, 126, 656) configurable in at least an extended bipolar configuration and at least an alternative bipolar or unipolar configuration differing from the extended bipolar configuration, at least one left ventricular electrode (134, 134', 134", 134"', 654a, 654b, 654c, 654d, 655) defining a cathode of the extended bipolar configuration and a right ventricular electrode (126, 656) defining an anode of the extended bipolar configuration; energy delivery circuitry (730, 735) coupled to the lead system; sensing circuitry coupled to the lead system; a controller coupled to the sensing circuitry and the energy delivery circuitry, the controller configured to execute program instructions for sensing cardiac electrical activity and delivering cardiac resynchronization therapy to the heart in accordance with programmed pacing parameters including a non-zero intraventricular delay, the controller configured to deliver a pace pulse to the at least one left ventricular electrode defining the cathode of the extended bipolar configuration; and characterized by a detector coupled to the sensing circuitry and the controller, the detector configured to sense for a response to the pace pulse and detect anodal stimulation of the right ventricle based on the sensed response; and the controller is configured to selectably switch from a current extended bipolar pace vector to an alternative bipolar or unipolar pace vector without ganging an additional anode electrode with the right ventricular electrode to mitigate or eliminate detected anodal stimulation of the right ventricle.