What is special in de-novo left atrial flutter patients? A comparison to post-ablation left atrial flutter cases

Abstract Background Left atrial flutter (LAF) can arise following pulmonary vein isolation (PVI) or following PVI with additional extra-PV ablations (PVI+), because both approaches may inadvertently create arrhythmogenic substrates. In a minority of patients however, LAF presents as a de-novo arrhythmia without preceding left atrial ablations or interventions. This group of patients with de novo LAF is not well characterized. Purpose To compare patient characteristics, pathophysiological mechanisms and ablation outcomes in patients with de-novo LAF ("deNovo" group) to patients with LAF arising after previous left atrial ablation procedures ("Post-ablation" group). Methods We included patients undergoing LAF ablation between Jan 2021 and Jun 2023 at our institution. Baseline and procedural data, including arrhythmia mechanism and lesion sets, were collected, and patients were followed with 7-day Holter ECG at 3, 6, and 12 months. The primary endpoint was recurrence of any atrial arrhythmia lasting longer than 30 seconds. Results 147 patients with LAF were analyzed (median age 71 years, IQR 65-75 years, 65% male). Of those, 32 (22%) presented with deNovo LAF, and 115 (78%) with post-ablation LAF (54 patients post PVI, 61 patients post PVI+). Patients in the deNovo group were older (74 years vs. 70 years, p=0.037), more often female (50% vs. 30%, p=0.058) and had a lower BMI (26.0 vs. 27.1, p=0.025). In 28% of the patients in the deNovo group, no AF had been diagnosed before. The most prevalent dominant arrhythmia mechanisms in the deNovo group was localized septal micro-reentry (47%), followed by perimitral flutter (31%), roof dependent flutter (16%) and unmappable (6%). In the post-ablation group, the most prevalent dominant arrhythmia mechanism was perimitral flutter (40%), followed by localized septal micro-reentry (32%), roof dependent flutter (24%), and unmappable (4%). Patients in the deNovo group more frequently received an anterior mitral isthmus line (72% vs. 51%, p=0.044) and fewer substrate modifications (6% vs. 26%, p=0.015). Freedom from any atrial arrhythmia at 12 months was similar for the two groups (deNovo 46%, CI 30%-69%, Post Ablation 51%, CI 49%-69%, p=0.42, Figure). Conclusion Patients referred for deNovo LAF ablation represent a special patient cohort that is older, more often female, with lower BMI, and in 28% of the patients without prior AF diagnosis. Localized septal micro-reentry was the most common arrhythmia mechanism in this cohort and an anterior mitral isthmus line was performed in 72% of the patients. Arrhythmia-free survival was similar when compared to patients referred for LAF after prior left atrial ablation.