Characteristics, pathophysiological mechanisms, and ablation outcomes of patients with de novo left atrial flutter compared with patients with postablation left atrial flutter

Background Left atrial flutter (LAF) most commonly arises in patients with previous left atrial ablation or surgery. Rarely, it can present as a de novo arrhythmia without previous interventions. Objective We aimed to compare patient characteristics, pathophysiological mechanisms, and ablation outcomes of patients with de novo LAF with those of patients with postablation LAF. Methods Patients undergoing LAF ablation between January 2021 and June 2023 were included. Baseline data, arrhythmia mechanisms, and ablation targets were collected. Patients were followed with 7-day Holter electrocardiograms at 3, 6, and 12 months. The primary endpoint was arrhythmia recurrence after a 90-day blanking period. Results A total of 147 patients with LAF were analyzed (median age 71 years; 65% men). Of those, 32 (22%) presented with de novo LAF, and 115 (78%) presented with postablation LAF. Patients in the de novo group were older (74 years vs 70 years; P = .037), were more often women (50% vs 30%; P = .058), and had a lower body mass index (26.0 vs 27.1; P = .025). In 28% of patients in the de novo group, atrial fibrillation had not been diagnosed before the procedure. The dominant arrhythmia mechanisms in the de novo group were anteroseptal localized reentry (44%), followed by perimitral flutter (31%) and roof-dependent flutter (16%). Freedom from any atrial arrhythmia at 12 months was 46% (95% confidence interval 30–69) in the de novo and 50% (95% confidence interval 41–62) in the postablation group ( P = .39). Conclusion Patients with de novo LAF are older and leaner than patients with postablation LAF, and the predominant arrhythmia mechanism is anteroseptal localized reentry. Arrhythmia-free survival is similar in both groups.