Nonlinear synchronization assessment between atrial and ventricular activations series from the surface ECG in atrial fibrillation

► Synchronization between atrial and ventricular activations in atrial fibrillation has been quantified noninvasively from real ECG recordings. ► Nonlinearity in both atrial and ventricular activation series was assessed and cross-sample entropy demonstrated its usefulness as synchronization marker. ► Synchronization was higher for paroxysmal than for persistent atrial fibrillation, thus varying as a function of the atrial activity temporal organization. ► Clinically useful information could be yielded to improve current rate control therapies by considering atrial activity organization.