Use of Normalized Correlation Function to Discriminate Outcome of Persistent Patients Undergoing Electrical Cardioversion

Atrial activity (AA) during atrial fibrillation (AF) is a process characterized by different short- and long-term recurrent behaviors. In this work we hypothesize that the features derived from these behaviors contain an information on the lead locations that discriminate the most between persistent AF patients recurring after electrical cardioversion from those who do not. Body surface potential maps (BSPMs, 184 electrodes) were recorded in 63 patients in persistent AF prior to electrical cardioversion (32 recurrences after 4-6 weeks). A correlation function (CF) was computed for each electrode, and normalized in order to make it independent of its magnitude. Finally, the first min and max values of the normalized CF from each electrode were used to discriminate patients outcome. The corresponding spatial maps showed that electrodes with the largest values of normalized CF are located on the front of the torso, centered around V1. A Wilcoxon rank-sum test was used to compare maps of recurrent and non-recurrent AF patients and find electrodes with significantly different magnitude. A significant difference was observed on the upper and lower parts of the torso, with higher values for the non-recurrent AF patients (higher recurrence of the underlying AA propagation patterns). When looking at the energy computed on each electrode, this parameter was not able to distinguish among the two groups.