Dynamic left atrial substrate in patients undergoing redo ablation for atrial fibrillation recurrence
C Martignani, A Spadotto, G Massaro, I Diemberger, A Angeletti, L Bartoli, M Ziacchi, M BiffiAbstract
Background
Despite high acute success rates of pulmonary vein isolation (PVI), recurrence of atrial fibrillation (AF) remains common, reflecting both pulmonary vein (PV) reconnection and progressive atrial disease. Progressive electrical and structural remodeling of the atrial myocardium can generate new low-voltage areas (LVAs) that perpetuate arrhythmia even in the absence of PV reconnection. Understanding this dynamic process may help refine redo ablation strategies toward substrate modification.
Methods
We retrospectively analyzed 82 consecutive patients (mean age 63 ± 10 years, 62% male) undergoing redo AF ablation at least 9 months after successful PVI for documented recurrence. High-density bipolar voltage mapping was performed during sinus rhythm using a multipolar mapping catheter. LVAs were defined as bipolar voltage <0.5 mV and quantified as a percentage of left atrial surface. Maps from redo procedures were compared with index procedure data when available. Clinical variables associated with substrate progression and arrhythmia recurrence were evaluated.
Results
At redo, 69% of patients demonstrated new or enlarged LVAs compared with baseline. LVAs were most commonly located in the posterior wall and septal regions, extending beyond prior ablation lesions. PV reconnection was present in 58% of patients, frequently coexisting with progressive LVAs. Patients with persistent AF, larger left atria, and longer time since initial ablation were more likely to develop new LVAs (p<0.01). In 21% of patients, recurrence occurred despite durable PV isolation, emphasizing a non-PV substrate. Substrate-guided ablation targeting new LVAs restored sinus rhythm in 79% at 12 months, significantly higher than in those with PV reisolation alone (65%, p=0.04).
Conclusion
Atrial substrate progression is frequent after AF ablation and contributes to recurrence independently of PV reconnection. Repeat procedures should include systematic high-density voltage mapping to identify evolving low-voltage substrate and allow a tailored, substrate-guided ablation approach that addresses both PV reconnection and ongoing atrial remodeling.