Beat-to-beat variability of P-wave in patients suffering from atrial fibrillation

The aim of this paper was to analyze the P-wave variability over time in patients suffering from Atrial Fibrillation (AF). Behind some time-domain and morphological features of the P-wave template, two novel indexes of P-wave variability have been estimated: one based on the cross-correlation coefficients among the P-waves (Correlation Index, CI), and one associated to variation of P-waves amplitude (Amplitude Index, AI). These indexes were estimated in two experimental models: patients suffering from persistent AF respect to control subjects and patients developing post-operative AF (POAF) after coronary artery bypass grafting respect to patients without POAF. The control group resulted to be characterized by shorter P-wave duration and by a less amount of fragmentation and variability, respect to AF patients (with a sensitivity and specificity of 98.4% and 95 % respectively). Also P-wave features resulted to be different for patients with POAF respect to patients without. In conclusion the quantification of the P-wave variability over time can add information in the understanding of the association between the anatomical atrial substrate and atrial arrhythmias.