Temporal Stability/Optimal Mapping Duration
The region with the highest frequency of each propagation pattern may be considered as reflecting an optimum target for ablation. This was identified using the 30% cut off to identify the relevant zone on maps of increasing duration up to 30 seconds. Each vertex of the anatomy contained within and outside this region (at 30% cut off) was used to calculate the kappa statistic to quantify the consistency between these zones against the zone identified during a full 30 second segment. Kappa values were calculated and plotted at both 1-second and 5-second increments with a value of 0.8 considered excellent consistency compared to the result obtained at 30-seconds. The duration at which a kappa value of 0.8 was reached was extracted for each map and used for comparisons.
In a subset of 15 patients, additional analyses were undertaken using alternative methods to confirm that the results obtained were consistent between methods used. LIA, LRA, and FF were quantified for occurrence frequency, percentage time present and percentage of the chamber surface area affected (for FF only frequency was assessed) at increasing durations, also in 1-second increments up to 30-seconds. At each incremental recording duration, the percentage change in each variable was calculated. For occurrence frequency the results for every possible combination of maps of increasing duration within the 30s recording were compared (e.g. the frequency of a pattern was measured over 5-seconds and compared with all possible maps of 5-second duration within the full 30-second recording). For occurrence time and surface area a 5s moving average at 1s increments was calculated. Heatmaps were created for each pattern allowing a visual representation of the effect of duration on variability.