The idea of analyzing P wave inscriptions to discriminate between patients with different diseases is not new. Whereas standard approaches deal mainly with an analysis of the duration of the P wave, there is an increasing interest for the P wave morphology. Detailed analysis of the low voltage P wave will require a hardware setup that enables high-quality signal acquisition with low noise interference in combination with an ECG subtraction technique. The feasibility of the surface ECG to detect the presence of an abnormal electrophysiological substrate in the atrial myocardium as well as to localize ectopic atrial rhythms will be enhanced by use of P wave morphological analysis.