An example of a system for pacing through multiple electrodes in a ventricle includes a sensing circuit to sense cardiac signal(s), a pacing output circuit to deliver pacing pulses, a heart sound sensor to sense a heart sound signal, and a control circuit to control the delivery of the pacing pulses. The control circuit includes a heart sound detector to detect heart sounds using the heart sound signal, an electrical event detector to detect cardiac electrical events using the cardiac signal(s), a measurement module to measure an optimization parameter using the detected heart sounds, an optimization module to perform an optimization procedure using the optimization parameter in response to an optimization command, and an optimization initiator to generate the optimization command. The optimization procedure includes selection of a single electrode or a plurality of electrodes from the multiple electrodes in the ventricle for pacing that ventricle.
