Are drivers recurring or ephemeral? observations from serial mapping of persistent atrial fibrillation

Figure 1. Visualization of recurrence measures. For repeated measures at the same anatomical site across two sequential studies, we examined the presence of drivers and categorized them into four classes: recurring drivers, non-recurring drivers, latent drivers, and non-drivers. Additionally, if a site exhibited a driver across all three studies, we classified it as having a multi-recurring driver.

Figure 2. Number of drivers found per study date in 18 canines. The number of drivers increased with time in AF between the 1- and the 6-month studies (P = 0.04, t-test). Driver totals for 1-, 3-, and 6-months were 5.2 ± 2.8, 6.4 ± 2.5, and 6.9 ± 2.3, respectively. The mean number of drivers for any given animal and study was 6.3 ± 2.5.

Figure 3. Identified drivers stratified by anatomical site, measured animal (n = 18), and electrophysiology study date. Each block corresponds to an anatomical site, with colour indicating the existence and type of driving mechanisms. The line plots show the fraction of the above blocks with drivers at the given study date. For some sites, we could not classify the site due to insufficient data quality, early termination of non-reinducable AF, or animal unavailability for study at the desired date. (A) identified drivers in the LA. (B) identified drivers in the RA.

Figure 4. Observed drivers by recurrence type and anatomical sites. We defined recurring drivers as sites where a driver was observed in two consecutive studies. Sites where greater than 50% of drivers were recurring were the roof and the appendage. Recurring drivers constituted 73% and 41% of all drivers in the LA and RA, respectively.

Figure 5. Distributions of cycle length as a function of driver recurrence type. We observed a relationship between types with respect to cycle length for both recurrence and multi-recurrence (P < 0.01 and P < 0.0001 respectively, ANOVA). We also observed sites with recurring and multi-recurring drivers to have significantly shorter cycle lengths than other sites, even for non-recurring and singly recurring drivers. This observation supports cycle length as a marker for both driver recurrence and multi-recurrence.

Figure 6. Relationship between driver recurrence type and LGE-MRI enhancement. For each animal (n = 6), enhanced regions of LGE-MRI were manually segmented as fibrotic. We excluded animals without all three studies, and we excluded two animals that lacked high-quality MRI. For each site, we calculated what percentage of area within 5 mm of the measurement centre was fibrotic. There was no relationship between driver recurrence type and enhancement (P = 0.74, ANOVA). We found that sites with a driver had higher levels of enhancement than sites without drivers (P = 0.04, Wilcoxon signed rank test). (A) recurrence type and enhanced area. (B) existence of driver and enhanced area.