1. An implantable electrical cardiac treatment device comprising: first, second, and third electrodes, the second electrode provided at a first distance from the first electrode along a lead assembly, the third electrode provided at a second distance from the first electrode along a lead assembly; and operational circuitry electrically coupled to the first, second and third electrodes such that sensing can be performed using any pair chosen therefrom; wherein the operational circuitry is adapted to perform the following steps: observe a signal metric between at least two of the following sensor pairs: first-second, first-third, and second-third; select a default sensor pair for use in cardiac signal analysis by determining which pair performs the best as measured by the signal metric.