An implantable medical device system for delivering a pacing therapy, comprising: a pacing device comprising: one or more electrodes (224, 226) for sensing cardiac signals and delivering the pacing therapy, the pacing therapy comprising a non-ambulatory pacing therapy and an ambulatory pacing therapy; a processor configured to control delivery of the pacing therapy via the one or more electrodes; and an electromechanical, EM, sensor to sense a non-ambulatory EM signal of the patient in response to the delivered non-ambulatory pacing therapy and an ambulatory EM signal of the patient in response to the delivered ambulatory pacing therapy; a plurality of external electrodes configured to being positioned along a torso of a patient to sense electrical activity of tissue of the patient; and a computing apparatus electrically coupled to the plurality of external electrodes, wherein the computing apparatus is configured to determine a time period between a non-ambulatory ventricular pace event and a mechanical response based on the non-ambulatory EM signal; and determine an optimal EM response time based on the determined time period during delivery of non-ambulatory pacing therapy by the pacing device, and wherein the processor of the pacing device is further configured to determine a current EM response time in response to the sensed ambulatory EM signal, compare the current EM response time determined by the processor of the pacing device during delivery of ambulatory pacing to the optimal EM response time determined by the computing apparatus during delivery of non-ambulatory pacing therapy by the pacing device, and adjust a pacing parameter setting for delivering the ambulatory pacing therapy in response to the comparing. one or more electrodes (224, 226) for sensing cardiac signals and delivering the pacing therapy, the pacing therapy comprising a non-ambulatory pacing therapy and an ambulatory pacing therapy; a processor configured to control delivery of the pacing therapy via the one or more electrodes; and an electromechanical, EM, sensor to sense a non-ambulatory EM signal of the patient in response to the delivered non-ambulatory pacing therapy and an ambulatory EM signal of the patient in response to the delivered ambulatory pacing therapy; a plurality of external electrodes configured to being positioned along a torso of a patient to sense electrical activity of tissue of the patient; and a computing apparatus electrically coupled to the plurality of external electrodes, wherein the computing apparatus is configured to determine a time period between a non-ambulatory ventricular pace event and a mechanical response based on the non-ambulatory EM signal; and determine an optimal EM response time based on the determined time period during delivery of non-ambulatory pacing therapy by the pacing device, and wherein the processor of the pacing device is further configured to determine a current EM response time in response to the sensed ambulatory EM signal, compare the current EM response time determined by the processor of the pacing device during delivery of ambulatory pacing to the optimal EM response time determined by the computing apparatus during delivery of non-ambulatory pacing therapy by the pacing device, and adjust a pacing parameter setting for delivering the ambulatory pacing therapy in response to the comparing.