RETRO-MAPPING: A New Approach to Activation Mapping in Persistent Atrial Fibrillation Reveals Evidence of Spatiotemporal Stability

Abstract

Background - The mechanisms underlying AF remain controversial. We developed RETRO-Mapping to characterize activation wavefronts by direction and uniformity, accumulating data as an orbital plot and analyzed as frequency histograms. We applied this technique to patients undergoing AF ablation to determine if AF activation is random. Methods - Patients undergoing persistent AF ablation were recruited and an AFocusII was positioned at multiple left atrial locations and kept steady for 1min to collect electrograms. The AFocusII was returned to the original site and position after >10mins for a repeat 1min data collection. Data was exported to custom RETRO-Mapping software, and 30sec consecutive time windows at each location were studied using frequency histograms of wavefronts. R50 (the range in degrees containing 50% of the total activation) was used as a method to enable statistical comparisons of activation patterns. Electrogram characterization into categories of complex fractionated atrial electrograms (CFAEs) by Ensite Precision was subjected to similar analysis. Results - Consecutive 30secs segments were studied at 161 locations in 18pts. Mean overlap between frequency histograms was 79.5%±7.7 (95%CI 78.3 to 80.7). 9 patients underwent delayed mapping at the same location, and mean overlap between the first 30sec and >10min interval was 73%±11.8 and 71.9%±13.6 for consecutive 30sec segments. Stability was confirmed using R50 (Bland-Altman mean difference: 0.87; LOA: -34.0 to 36.0; r=0.005; P=0.95). A greater variance in R50 was observed between different locations within a patient than the variance within the same locations (ICC=0.765; p<0.0001), and similarly for both CFAE and bipolar voltage (P<0.0001). A larger area containing CFAE (80-120ms) showed weak positive correlation with increasing R50 (r = 0.36, P<0.001) suggesting a relationship between activation pattern and electrogram characteristics. Conclusions - There appears to be preferential activation patterns during persistent AF indicating spatiotemporal stability. This has important implication to our mechanistic understanding of persistent AF.