Abstract Body (Do not enter title and authors here):
Introduction: Atrial fibrillation (AF) and atrial flutter (AFL) are commonly observed cardiac manifestations of myotonic muscular dystrophy (MMD). However, there is sparse data available describing the safety and efficacy of atrial ablation procedures in this population.

Goals/Aims: This study aims to describe the safety and efficacy of AF or AFL ablation procedures in a cohort of MMD patients at a large, academic institution.

Methods/Approach: All MMD patients who underwent AF or AFL ablations at a single institution between 2019 and 2023 were identified and analyzed using summary statistics.

Results/Data: Between January 2019 and December 2023, ten patients with MMD underwent either AF or AFL ablation. Of these ten patients, 8/10 had type 1 MMD, 2/10 had type 2 MMD, and 3/10 were female. Median age at time of AF/AFL diagnosis was 34 years [IQR: 26, 48] and median age at time of ablation was 40 years [IQR: 30, 52]. All patients were on direct oral anticoagulants for >3 weeks prior to and post ablation, 7/10 were on rate control medications and 5/10 were on rhythm control medications (2 class Ic, 3 class III). Indications for ablation included inappropriate ICD shocks in 3 patients, tachycardia-induced cardiomyopathy in 3 patients, arrhythmia-related symptoms in 3 patients, and patient preference in 1 patient. During the study period, 6/10 patients had cavotricuspid isthmus (CTI) AFL ablations, 2/10 patients had pulmonary vein isolation (PVI) ablations for AF, and 2/10 patients had simultaneous CTI and PVI ablations. No procedural complications were observed, though complications in the post-procedural period included aspiration pneumonia in 1 patient, aspiration and agitation necessitating prolonged intubation in 1 patient, and altered mental status prompting close observation and ultimately a negative stroke work-up in 1 patient. The majority of patients (7/10) had recurrent AF/AFL at a median 39 days post-ablation [IQR: 18, 270]. Four patients underwent a second AF or AFL ablation.

Conclusion: Ablation of AF/AFL can be performed safely in MMD patients. However, anesthesia related complications and early recurrences of atrial arrhythmias warrant close consideration during evaluation for atrial ablation.