A control system for an implantable cardiac therapy device, the device defining a plurality of sensing vectors including at least one impedance sensing vector and operating under a set of a plurality of variable operating parameters that define conditions for delivery of therapy and wherein the control system evaluates signal quality from the at least one impedance sensing vector and, if the quality is sufficient to discern valvular events, the control system adjusts the set of operating parameters to dynamically improve cardiac performance, including synchrony with valvular events, and if the quality is insufficient to discern valvular events, but sufficient to discern peaks, the control system adjusts the set of operating parameters to dynamically improve cardiac performance independent of valvular events, and if the quality is insufficient to discern peaks, the control system adjusts the set of operating parameters to induce cardiac performance towards a defined performance goal.