A cardiac rhythm management system selects one of multiple electrodes associated with a particular heart chamber based on a relative timing between detection of a depolarization fiducial point at the multiple electrodes, or based on a delay between detection of a depolarization fiducial point at the multiple electrodes and detection of a reference depolarization fiducial point at another electrode associated with the same or a different heart chamber. Subsequent contraction-evoking stimulation therapy is delivered from the selected electrode.