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.