Serum Magnesium Levels and Risk of Atrial Arrhythmia Recurrence After Catheter Ablation: A Prospective Multicenter Cohort Study

Background Serum magnesium (Mg) plays an important role in cardiac electrophysiology, but its association with atrial arrhythmia recurrence after catheter ablation remains unclear. Objective To investigate the association between preprocedural serum Mg levels and atrial arrhythmia recurrence after AF ablation. Methods We included 5,789 patients undergoing AF ablation from the prospective China-AF registry. Patients were categorized into tertiles according to baseline serum Mg levels: low (<0.84 mmol/L), intermediate (0.84–0.90 mmol/L), and high (>0.90 mmol/L). The primary outcome was atrial arrhythmia recurrence. Cox proportional hazards models and restricted cubic spline analyses were used to evaluate the association between serum Mg levels and recurrence risk. Results During a median follow-up of 372 days, recurrence occurred in 40.5%, 36.5%, and 41.1% of patients in the low, intermediate, and high Mg groups, respectively. Compared with the intermediate group, both low and high Mg levels were associated with increased recurrence risk (low versus intermediate: hazard ratio [HR], 1.09 [95% CI, 1.01–1.21]; high versus intermediate: HR, 1.12 [95% CI, 1.01–1.25]). Restricted cubic spline analysis demonstrated a significant nonlinear association between serum Mg levels and recurrence risk (P for nonlinearity=0.003), with the lowest estimated risk observed within the intermediate range of serum Mg values. Findings were consistent across subgroup, sensitivity, and competing-risk analyses. Conclusions Preprocedural serum Mg levels were nonlinearly associated with atrial arrhythmia recurrence after AF ablation. Serum Mg may serve as a readily available marker of recurrence risk and warrant further investigation into the mechanisms linking Mg homeostasis and post-ablation outcomes.