3. Results:

Demographics and clinical characteristics:

A total of 419 patients had an ablation at Mayo Clinic for AAFL from January 2017 to June 2022. A total of 13 patients were excluded due to denied research authorization. Additionally, 19 patients were lost to follow-up during the 90-day blanking period and excluded, resulting in a total sample size of 387. The median follow-up time for patients was 25.7 months (95% CI 23.7, 32.3).
The demographics and clinical characteristics are given in Table 1 . The median age was 68.0 (IQR 60.0, 74.0), and 32.6% of patients were female.
Ablation Characteristics : Bidirectional block following a linear line was confirmed at the end of the ablation in 66.06% (255/386) of the patients. In 1.2% (5/386) of the patients, only unidirectional block could be achieved. In 5.6% (22/386) of the patients, bidirectional block could not be achieved at the end of the ablation. In 26.9% (104/386) of the patients, the confirmation of the bidirectional block was not documented.

Recurrence-free survival:

Recurrent events following the ablation occurred in 226/387 (58.4%) patients after a median of 8.5 months post-ablation (max 57.8 months), of which 151/226 (66.8%) occurred within the first year . During the study period, 11/387 patients died, 9 of whom experienced recurrence prior to death. The median recurrence-free survival (RFS) time was 16.6 months (95% CI 13.2, 20.0). The 1-year RFS was 57.2% (95% CI 52.2%, 62.7%).
Figure 1 shows the Kaplan-Meier curve for the probability of RFS over time.

Recurrence-free survival based on acute termination status:

Acute termination occurred in 324/387 (83.7%) during the ablation.Figure 2 shows the Kaplan-Meier curve for the probability of RFS over time-based on acute termination or lack of termination during ablation. For patients with acute termination, the 1-year RFS rate was 58.9% (95% CI 53.5%, 64.9%). For patients without acute termination, the 1-year RFS rate was 49.0% (95% CI 37.9%, 63.4%). The RFS was not significantly different based on acute termination status (p = 0.11).

Recurrence:

For patients who experienced recurrence following the ablation, 48.7% experienced a different AAFL, and 40.7% experienced AF. 51.8% of patients were cardioverted, 14.6% had an AV node ablation, 35.0% underwent a repeat ablation (Table 2), and 44.7% were on anti-arrhythmic drugs after index ablation.