Non-linear dynamics of atrial rate during atrial fibrillation assessed by recurrence plot analysis

The aim of this study was to use Recurrence Plot Analysis to test the hypothesis of deterministic non-linear dynamics of Atrial Period (AP) during type I Atrial Fibrillation (AF) (Wells´ classification). The authors used three variables to quantify Recurrence Plots: Percent Recurrence (PR), Percent Determinism (PD) and Entropy of Recurrences (ER). They analyzed bipolar intra-atrial electrograms of electrically induced AF recorded in 3 different atrial sites in 15 informed subjects. The AP of each each site was obtained by using a peak detection algorithm based on threshold crossing. The authors compared the real data results with those obtained from their stochastic surrogate series (phase randomization). PR, PD and ER values obtained for the surrogate data were significantly lower than those values from original data, confirming the hypothesis of a nonlinear deterministic dynamics of the atrial depolarization period during AF