Multiple P-wave Morphologies in Paroxysmal Atrial Fibrillation Patients During Sinus Rhythm: A Simulation Study

P-wave in electrocardiographic (ECG) signals represents the activation of the atrial substrate. Its shape is influenced by the origin of the sinus rhythm (SR) and the conduction of each part of the atria and thus the analysis of its morphology (PWM) can reveal information related to the atrial conduction routes. Recently, the analysis of the PWM from PAF patients during SR, revealed the presence of a distinct secondary morphology in a remarkable percentage of beats. We hypothesize that the variability on the PWM can be attributed to the coexistence of electrical remodeling and the transient modification of the conduction route which is the result of the shift of the stimulation site within the sinus node. In this study, the Courtemanche et al. model was incorporated in a 2D tissue of the left and the right atrium, while tissue heterogeneities were considered. Simulations were conducted, using the CHASTE platform, in normal and electrical remodeled tissue. In each simulation, the stimulation site was shifted within the sinus node. The results show that in electrical remodeled tissue, the shift of the stimulation site led to significant changes in the activation time in the atria compared with the healthy tissue. In future, the use of a 3D model of human atria is necessary in order to investigate the reproducibility of the results while the conditions under which the pacemaker location shifts must be also revealed.