A system can include a sensor array comprising a plurality of sensors configured to measure electrical activity across a body surface of a patient and generate electrical data characterizing the measured electrical activity. The plurality of sensors are arranged at predetermined locations for placement over the patient's body to define at least one predetermined zone of the patient's body that maps deterministically to at least one predetermined region of interest of at least one internal anatomical structure of the patient. A control system is configured to analyze the electrical data for the at least one predetermined zone to provide a surrogate estimate of electrical activity at the at least one predetermined region of interest. The control system also is configured to control delivery of a therapy to the patient based on the surrogate estimate of electrical activity at the at least one predetermined region of interest.