1. A system, comprising: a signal sensor circuit coupled to one or more physiologic sensors, the signal sensor circuit configured to sense one or more physiological signals and generate two or more signal metrics from the one or more physiologic signals; a stimulator circuit configured to generate and deliver electrostimulation to a heart; a controller circuit coupled to the signal sensor circuit and the stimulator circuit, the controller circuit configured to: program the stimulator circuit to generate and deliver electrostimulation according to a device parameter programmed to a specified value; configure the signal sensor circuit to sense the one or more physiological signals during the electrostimulation and generate the two or more signal metrics; and determine a desired value of the device parameter using one or more of respective sensitivity of the two or more signal metrics, respective variability of the two or more signal metrics, or a covariability between the two or more signal metrics, wherein the sensitivity of a respective signal metric is determined using a comparison of values of the same signal metric during stimulation sessions according to the device parameter programmed to different values.