Incidence and Predictors of Atrial Fibrillation After Cavotricuspid Isthmus Ablation for Typical Atrial Flutter.

Cavotricuspid isthmus (CTI) ablation is a highly effective treatment of typical atrial flutter (AFL). The emergence of new-onset atrial fibrillation (AF) following CTI ablation is clinically relevant but limited data exist regarding its predictors. The goal of this study is to investigate predictors of new-onset AF following CTI ablation. Patients who underwent CTI ablation between 2016 and 2022 were included. Baseline variables including left atrial volume index (LAVI), cardiac comorbidities, CHA₂DS₂-VASc score, and medications were collected. The primary outcome was the occurrence of new-onset AF after the index CTI ablation. New AF occurred in 44 (29%) of 153 patients at a median of 264 days. Patients who developed AF were more likely men (p = 0.046), had hypertension (p = 0.014), and higher LAVI (40.6 ± 12.2 vs 34.2 ± 9.5 mL/m², p <0.001). After adjusting for unbalanced covariates in a Cox multivariable model, protective predictors against developing new AF included female sex (HR 0.31, 95% CI 0.12-0.76, p = 0.011) and prior cardiac surgery (HR 0.22, 95% CI 0.07-0.72, p = 0.013) while increased LAVI (HR 1.02, 95% CI 1.00-1.05, p = 0.08) showed a trend towards higher risk of new AF. In conclusion, in this cohort of AF-naive patients undergoing CTI ablation for typical AFL, nearly one-third developed new-onset AF. Independent predictors of developing AF include male sex and no-prior cardiac surgery. These findings have clinical implications to the management of AFL patients, including for the decision to consider performing concomitant AF ablation in patients with higher risk features.