Abstract Body (Do not enter title and authors here): Background: Approximately 1 of 5 catheter ablations for atrial fibrillation (AF) are repeat procedures. Despite this, little is known about risk factors for recurrence in patients undergoing repeat ablation compared with those undergoing de novo ablation.

Objective: To compare predictors of AF recurrence following de novo and repeat catheter ablation.

Methods: To compare AF recurrence between those with and without prior ablation, we conducted a retrospective cohort study of patients undergoing catheter ablation for treatment of symptomatic and drug-refractory AF. In this analysis, early recurrence was defined as 30 seconds of AF, atrial flutter, or atrial tachycardia within a 3-month blanking period, while late recurrence was defined as recurrent arrhythmia at >3 months. Multivariable Cox proportional hazard regression analysis was used to identify independent factors associated with recurrence.

Results: Among 659 patients, 487 (mean age 63.3 +/- 10.1 years, 33% female, CHA2DS2-VASc 2.8 +/- 1.8, 62% paroxysmal) underwent de novo ablation and 172 (mean age 65.1 +/- 10.0 years, 34% female, CHA2DS2-VASc 3.1 +/- 1.9, 60% paroxysmal) underwent repeat ablation with average follow up of 24.4+/-18.4 months. Multivariable modeling revealed that left atrial volume index (LAVi) [HR 1.015, p<0.0001], body mass index (BMI) [HR 1.025, p=0.043], and early recurrence [HR 2.496, p<0.0001] were predictive of late recurrence in the de novo ablation cohort, compared to LAVi [HR 1.014, p=0.006] and early recurrence [HR 2.053, p=0.001] in the repeat ablation cohort. Age, sex, AF type (paroxysmal vs non-paroxysmal), obstructive sleep apnea, heart failure, CHA2DS2-VASc scores, and energy source (cryoballoon vs radiofrequency) were not predictive of recurrence in either cohort (p>0.05). There was a trend towards higher probability of recurrence following repeat ablation (log-rank p=0.052).

Conclusion: Predictors of late AF recurrence following de novo and repeat catheter ablation are similar at >2 years follow-up. The left atrial volume index and early recurrence are the strongest predictors of late recurrence.