A method and device for delivering therapy that includes an electrode to sense cardiac signals and to deliver a therapy, a therapy delivery module coupled to the electrode to deliver a therapy via the electrode in response to the sensed cardiac signals, a sensor emitting light and detecting emitted light scattered by a tissue volume adjacent the optical sensor to generate a corresponding detected light intensity output signal, a control module coupled to the sensor to control light emission of the sensor in response to delivering the therapy, and a controller coupled to the therapy delivery module and the sensor, the controller configured to determine tissue oxygenation measurements in response to the output signal, determine a tissue oxygenation trend in response to the tissue oxygenation measurements, and determine whether the delivered therapy restored cardiac hemodynamic function in response to the determined tissue oxygenation trend.