The Clinical Impact of Mitochondrial Autophagy on Very Late-Onset Recurrence after Catheter Ablation for Atrial Fibrillation

The mechanisms underlying very late-onset atrial fibrillation (AF) recurrence, defined as occurring more than 1 year after catheter ablation, are hypothesized to differ from those responsible for recurrence within the first year; however, this remains uncertain. Two investigations were conducted in patients undergoing AF ablation. First, non-targeted metabolome analysis was performed in 10 patients with very late-onset recurrence and 10 without recurrence. Second, based on metabolomic findings implicating autophagy, serum levels of the autophagy-related proteins Parkin, a marker of mitophagy, and ATG5, an indicator of bulk autophagy, were measured using ELISA. Associations between these variables and very late-onset recurrence were analysed. Among the 203 patients (mean age 70 years, 63% male), 16 experienced very late-onset recurrence during a mean follow-up of 954 days. Metabolome analysis identified 255 peaks (177 cations and 78 anions). Principal component analysis revealed a reduction in γ-glutamyl dipeptides, contributors to mitochondrial autophagy, in the recurrence group. A serum Parkin level below the median was independently associated with very late-onset recurrence (hazard ratio 3.82, 95% confidence interval 1.20-12.13, P = 0.023), after adjustment for left atrial diameter and diabetes mellitus. In contrast, ATG5 levels were not significantly associated. Parkin levels did not predict recurrence within the first year (log-rank P = 0.09). Reduced serum Parkin levels were independently associated with very late-onset recurrence following AF ablation, suggesting that impaired mitochondrial autophagy may contribute to the pathogenesis of long-term AF recurrence.