Mapping duration results
Figure 6 demonstrates the effect of increasing map duration on kappa statistic values for LIA, LRA and FF respectively compared to maps of 30 seconds. Analysis was conducted on all 124 recordings (62 in the LA and 62 in the RA) obtained. LIA showed the highest kappa value at all time periods with a value of 0.66 (0.57-0.70) at 5s, rising to 0.93 (0.91-0.95) at 25s. LRA demonstrated the lowest value of 0.32 (0.17-0.43) at 5s, with a maximum of 0.85 (0.79-0.91) at 25s. A kappa value of 0.8 can be considered excellent correlation. Figure 6D shows kappa values at 1-second increments for LIA, LRA and FF. A value for 0.8 was reached by 12-seconds (IQR 6) for LIA compared to 19-seconds (IQR 7) for FF (p<0.0005) and 22-seconds (IQR 8) for LRA (p<0.0005).
The duration of mapping required to achieve a kappa value of 0.8 was compared between the left and right atria, in patients with paroxysmal and persistent AF, before and after pulmonary vein isolation and in patients on or off amiodarone. There was no difference for any parameter between the left and right atria. In patients with persistent AF, LIA stabilised earlier than in patients with paroxysmal AF (11±6 versus 15±4, difference 4-seconds, 95% confidence interval 0.6-5.6, p=0.004). There was no difference between any groups for stability of LRA. The frequency of focal firing stabilised after 17.2±5.6 seconds following pulmonary vein isolation compared to 19.1±3.7 seconds prior to pulmonary vein isolation, a difference of 1.9-seconds (95% CI 0.3-3.6, p=0.023). Full results for all comparisons are in supplementary figures S6 and S7 and tables S1-S3.
Heatmaps for the subset of 15 patients are shown in supplementary figure S8. When measured as either a frequency, proportion of time the propagation pattern was present or a proportion of the atrial surface area that patterns occurred, variability in LIA fell rapidly, followed by FF and LRA. A significant degree of variability in LRA patterns was observed, particularly when measured as a proportion of the atrial surface affected up to durations of 20-25s.