System and atrial events detected classification process in a pacing system

A system for classifying signals sensed by an electrode of an implantable pacing system (10) positioned in an atrium of the heart (8) is presented. It includes a pulse generator (96) and a controller (74). The method includes collection of wave signals compounds atrial event signals P and R-wave in the far field. An intermediate shape factor histogram is generated on the basis of a shape signal. It includes a waveform factor histogram P and R wave intermediates, each having sets of signals. A histogram previously generated is weighted and combined with the intermediate histogram to create a representative histogram. The representative histogram is analyzed to determine if a minimum error margin between the histogram P wave and the R wave histogram The atrial event signals are classified according to the shape as signals P-wave or R-wave on the basis of the representative histogram.