Aims: Areas with complex fractionated electrograms are commonly targeted during ablation of persistent atrial fibrillation (AF). These signals are, however, found in most sampled areas of the left atrium (LA), implying the need for further differentiation.
Methods and results: Electrograms were recorded over 60 s at eight different LA endocardial sites in 10 patients with persistent AF, using a fully automated algorithm. These were analysed in sequential 2 s segments for activity, mean amplitude, continuous activity percentage, and dominant frequency (DF). All three time-domain measures differed significantly between the LA sites (P < 0.001), whereas DF did not. Activity, continuous activity percentage, and mean activity-amplitude were highest in the mid-coronary sinus and lowest on the posterior wall. In a pairwise analysis, there were significant differences in activity between all locations (P < 0.001-0.044). To visualize the spatiotemporal activity patterns, activity was plotted against amplitude. This revealed distinct activity patterns with large intra- and inter-individual differences.
Conclusion: There are significant activity gradients and distinct activity patterns within the LA in humans with persistent AF. Further work is required, however, to determine whether these findings signify areas with different roles and importance in AF maintenance.