Periprocedural Mortality Risk After Elective Atrial Fibrillation Ablation in Japan.

Importance: Evidence on the safety of atrial fibrillation ablation during rapid growth in both procedural volume and the number of hospitals performing it remains inconsistent. Although clinical registries and randomized trial meta-analyses report extremely low mortality, administrative databases have suggested rates up to 10-fold higher, with concerning temporal increases. Objective: To define the periprocedural mortality risk following elective atrial fibrillation ablation using a validated nationwide database and to determine whether this expansion was associated with diffusion-related safety penalties (ie, transient erosion of safety driven by a widening efficacy-effectiveness gap). Design, Setting, and Participants: This retrospective, nationwide, population-based cohort study used data from a nationwide administrative database of participating cardiovascular hospitals in Japan from April 1, 2012, to March 31, 2023. Analyses were conducted in 2025 to 2026, with follow-up through discharge from the index hospitalization for the primary outcome. Patients with atrial fibrillation who underwent scheduled elective catheter ablation with transseptal puncture were included. Exposures: Elective atrial fibrillation ablation. Main Outcomes and Measures: The primary outcome was in-hospital mortality during the index hospitalization. In-hospital mortality and other event rates are presented as proportions with exact (Clopper-Pearson) binomial 95% CIs. Multivariable analyses used Firth penalized logistic regression. Results: Among 618 024 catheter ablation procedures, 412 947 were elective atrial fibrillation ablations (median [IQR] patient age, 68 [60-74] years; 288 825 male patients [69.9%]) performed between 2012 and 2022. Annual procedural volume increased from 10 969 procedures in 2012 to 63 014 procedures in 2022. In-hospital mortality occurred in 119 patients (0.029%; 95% CI, 0.024%-0.034%), with a modest but statistically significant decline (P for trend = .04). Within 30 days of the procedure, deaths occurred during the index hospitalization in 91 patients (0.022%; 95% CI, 0.018%-0.027%) and during readmission in 72 patients (0.017%; 95% CI, 0.014%-0.022%). The most frequent concurrent complication among index-hospitalization deaths was cardiac tamponade (26 patients [21.8%]). In Firth penalized multivariable analysis, factors independently associated with in-hospital mortality included older age (odds ratio [OR], 1.04; 95% CI, 1.01-1.07), lower body mass index (OR, 0.94; 95% CI, 0.89-1.00), Charlson Comorbidity Index score of 3 or higher (OR, 4.59; 95% CI, 2.59-8.12), low institutional volume (OR, 2.52; 95% CI, 1.45-4.38), and preserved functional status (Barthel Index >90; OR, 0.11; 95% CI, 0.07-0.19). Conclusions and Relevance: In this Japanese nationwide registry study of 412 947 elective atrial fibrillation ablation procedures, in-hospital mortality was 0.029%, comparable to contemporary registry benchmarks. No evidence of a diffusion-related safety penalty was observed during rapid expansion.