Patient Characteristics and Map Segments Obtained
The characteristics of all patients recruited to the study are outlined in table 1. One patient (patient 9) was excluded from analysis as only organised atrial tachycardia could be induced when attending for the procedure. In all but one patient (patient 12), two 30-second maps of AF were obtained at baseline. Patient 12 had varying QRS morphology as a result of left bundle branch block and only one 30s segment could be obtained with sufficient quality of QRS-T wave subtraction to allow analysis. Maps following pulmonary vein isolation were obtained in 12 patients and a further 8 recordings were obtained following non-pulmonary vein ablation providing a total of 62 simultaneous AF recordings in the left and right atrium. Mapping duration and temporal variability analysis was performed on all maps obtained (a total of 124 maps including both chambers). Spatial variability analysis was performed by comparing the two 30s maps obtained at baseline in the 20 patients.
Spatial Variability
LIA demonstrated the greatest spatial stability with R2 of 0.83(0.71-0.88) across all maps analysed. This was consistent across both chambers with values of 0.81(0.75-0.88) and 0.84(0.61-0.88) in the LA and RA respectively. Median R2 for LRA and FF were 0.39(0.24-0.57) and 0.64(0.54-0.73) respectively. Multiple low frequency focal firings were seen widely distributed across the atrial surface (see figure 5). For high frequency FF, defined as occurring ≥10 times over the 30s, R2 was 0.83(0.68-0.85). Detailed results are outlined in table 2.
Stability of regions across both maps with the highest frequency patterns identified at 30% cut off was also greatest for LIA in both the LA and RA. Cohen kappa statistic for LIA in the LA and RA respectively was 0.75 (0.64-0.78) and 0.75 (0.58-0.79). Full kappa statistic results for all patients are outlined in table 3.
The anatomical regions with maximal LIA were the anterior and posterior LA (in 46% and 27% of maps respectively) and the lateral and septal RA (in 46% and 32% respectively). LRA showed similar distribution with the zone of highest LRA frequency in the posterior LA in 41% and the anterior LA in 34%. In the RA, the lateral wall was the most common site (in 37%) followed by the septum and posterior walls (each in 24%). A similar distribution was observed for FF, most commonly involving the anterior and posterior LA (in 34% and 29% respectively), followed by the LA septum (20%). In the RA, the highest frequency of FF was seen in the septum in 59% and the lateral wall in 22%.