A method and implantable medical device system for delivering a cardiac pacing therapy that includes suspending delivery of the LV cardiac pacing therapy and sensing far-field cardiac signals via one or more far-field sensing vectors formed between a plurality of electrodes positioned on a single-pass coronary sinus lead. Far-field signal features are determined in response to the sensed far-field cardiac signals, a first offset interval and a second offset interval are determined in response to the determined far-field signal features, and an AV delay of the LV cardiac pacing therapy is adjusted in response to the determined first offset interval and second offset interval. Delivery of the LV cardiac pacing therapy having the adjusted AV delay is subsequently resumed.