1. An implantable medical device for use in delivering cardiac resynchronization therapy to a patient's heart, wherein the cardiac resynchronization therapy is delivered based on a plurality of device parameters, the device comprising: a sensing module configured to monitor at least an intracardiac impedance between at least two electrodes to provide an intracardiac impedance signal; a therapy delivery module configured to deliver cardiac therapy to the patient's heart; and a control module coupled to the sensing module and the therapy delivery module and configured to: deliver cardiac resynchronization therapy to a patient at a plurality of options for at least one of the device parameters; acquire selection data relating to each of the plurality of options for the at least one device parameter for at least one cardiac cycle, wherein acquiring the selection data at each of the plurality of options of the device parameter comprises: acquiring, at each of a plurality of electrode vector configurations, an intracardiac impedance signal, extracting a plurality of measurements from the intracardiac impedance signal for each of the plurality of electrode vector configurations, and determining selection data for each of the plurality of electrode vector configurations based on and corresponding to each of the plurality of extracted measurements from the intracardiac impedance signal; provide a score for each of the plurality of options of the device parameter based on the acquired selection data determined based on and corresponding to each of the plurality of extracted measurements for each vector configuration; and select an option of the plurality of options of the device parameter based on the scores for the plurality of options of the device parameter for delivery of cardiac resynchronization therapy to the patient.