Abstract: The present invention thus provides a simple and automatic method for determining an optimal AV interval and/or range of AV intervals for, in an exemplary embodiment, LV-only pacing. Such a method provides significant advantages for patients while reducing burdens related to post-implant follow-up by clinicians in that it greatly reduces the need for doing echocardiographic-based AV interval optimization procedures as well as providing a way to dynamically optimize AV intervals as the patient moves about their activities of daily living (ADL).