Repeat atrial fibrillation ablation using focal pulsed field energy: feasibility, and procedural safety

Background Recurrence of atrial fibrillation (AF) after initial catheter ablation remains common, often requiring repeat procedures. Thermal ablation techniques are limited by the risk of collateral injury and by reduced lesion durability in regions with thicker myocardium. Pulsed field ablation (PFA), due to its non-thermal and relatively tissue-selective mechanism, may enhance both procedural safety and effectiveness in redo AF ablation. Objective To evaluate the feasibility, and procedural safety of focal monopolar PFA in repeat AF ablation procedures. Methods This study included 180 consecutive patients (mean age 69.6 ± 10.0 years; 43% female; 28% paroxysmal AF) undergoing repeat AF ablation using focal monopolar PFA. Forty-three patients had previously undergone pulmonary vein isolation (PVI) alone using radiofrequency, cryoballoon, or single-shot PFA, whereas the remaining patients had prior linear left atrial ablation. All procedures were performed with the CENTAURI system using contact-force sensing catheters integrated into 3D electro-anatomical mapping. Each PFA application delivered 25 A for a total of around 10 s. Intravenous nitroglycerine was administered before ablation at sites where coronary vasospasm was a possible risk. Lesion sets were tailored based on conduction gaps and additional left atrial arrhythmogenic substrate. Results Re-isolation of the pulmonary veins was performed in 76 patients, 138 patients underwent substrate modification, including closure of conduction gaps or creation of new linear lesions. The most frequent targets were the anterior wall (73 new anterior mitral isthmus lines, 18 gap closures of previous ablation lines), posterior wall (80 complete box isolations and 12 partial or gap ablations), and roof line without box isolation (19 new lesions and 11 gap ablations). Superior vena cava isolation was performed in 25 patients with extra-PV triggers. Bidirectional block or re-isolation of all targeted structures was achieved in all but two cases involving the anterior mitral isthmus line. Mean total procedure duration was 175 ± 48 min, with a median ablation time of 550 (IQR 350–880) s, median fluoroscopy time of 2.4 (IQR 1.5–3.7) min, and median fluoroscopy dose of 33 (IQR 22–60) cGy·cm². Complications occurred in 9 patients (5.0%). Vascular access complications included two groin hematomas and one retroperitoneal bleed. There was one coronary air embolism and one peri-procedural ischemic stroke. Two cases of coronary vasospasm occurred during left atrial ablation and resolved after additional intravenous nitroglycerine administration. Two patients developed transient phrenic nerve palsy, both fully resolving during the hospital stay. Conclusions Repeat AF ablation using focal monopolar PFA is feasible. The technique enabled effective pulmonary vein re-isolation and individualized substrate modification across different atrial regions, with low fluoroscopy exposure and an acceptable safety profile.