Background: Data related to electrophysiologic characteristics of atypical atrial flutter (AFL) following atrial fibrillation (AF) ablation and its prognostic value on repeat ablation success are limited. Methods: We studied consecutive patients undergoing a repeat LA ablation for either recurrent AF or atypical AFL, following 3 months after index AF ablation, between January 2012 and July 2019. The demographics, procedural data, complications, and 1-year arrhythmia-free survival rates were recorded for each subject after the first repeat ablation. Results: Of the total 336 included patients, 102 underwent a repeat ablation for atypical AFL and 234 for recurrent AF. The mean age was 63.7  10.7 years, and 72.6 % of patients were male. The atypical AFL cohort had significantly higher LA diameters (4.6 vs. 4.4 cm, p=0.04) and LA volume indices (LAVi; 85.1 vs. 75.4 ml/m2, p=0.03) compared to AF patients at repeat ablation. Atypical AFLs were roof-dependent in 35.6% and peri-mitral in 23.8% of cases. Major complications at repeat ablation occurred in 0.9 % of the total cohort. Arrhythmia-free survival at one year was significantly higher in the recurrent atypical AFL than the recurrent AF cohort (75.5 vs. 65.0 %, p=0.04). Conclusion: In our series, roof-dependent flutter is the most common form of atypical atrial flutter post AF ablation. Patients developing atypical AFL after index AF ablation have greater LA dimensions than patients with recurrent AF. The success rate of first repeat ablation is significantly higher among patients with recurrent atypical AFL compared to recurrent AF after index AF ablation.

Introduction: There are limited data describing the experience of index radiofrequency (RF) vs. cryoballoon (CB) ablation for atrial fibrillation (AF) among elderly patients in the United States. Methods: We conducted a retrospective analysis of patients > 75 years of age undergoing index AF ablation between January 2010 and March 2019 at our center. Major complications and efficacy, defined as freedom from any atrial tachyarrhythmia (ATA) lasting ≥30 seconds after one year of follow-up, were assessed in patients with index RF vs. CB ablation. Predictors of ATA recurrence at 1 year follow-up were also evaluated. Results: In our cohort of 194 patients, the mean age was 78 ± 3.1 years, 58.2% were men, and 39.4% had persistent AF. The mean left atrial (LA) diameter was 4.5 ± 0.7, while the mean CHA2DS2-VASc score was 3.5 ± 1.2. The majority (n=149, 76.8%) underwent RF ablation. The incidence of complications was similar in the two sub-groups (RF: 1.3% vs. CB: 2.2%, p=0.67). No significant difference in success rate at 1-year follow-up was found between patients receiving RF vs. CB ablation (59.7% vs. 66.7%, p=0.68). In a multivariable model adjusting for the relevant covariates only LA size [HR=1.64, CI: 1.15-2.34, p<0.01] was independently associated with ATA recurrence at 1year follow-up. Conclusion: In our cohort of elderly patients undergoing index CA for AF, RF ablation was the predominant modality with similar safety and efficacy relative to CB ablation. LA size was a significant predictor of ATA recurrence at 1year independent of index ablation modality.