Abstract Body (Do not enter title and authors here): Introduction: In pulmonary vein isolation (PVI), the carina is often refractory to ablation and require linear ablation, and some patients have epicardial connections.
Hypothesis: High-power Shor-duration (HP-SD) ablation can prevent gap formation, and high unipolar-voltage-area (HUV), defined >2.7 mV, will identify the epicardial connection site.
Aims: To investigate the impact of HP-SD ablation on durable PVI and the efficacy of HUV for the prediction of epicardial connection site.
Methods: Ninety-three atrial fibrillation (AF) patients who underwent successful PVI were enrolled. Forty-one patients underwent HP-SD ablation, while fifty-two patients underwent conventional ablation. First pass isolation was achieved in 66 patients, while the remaining 27 patients needed carina ablation. The epicardial conduction gap (EG) of the PVI line was defined as the continuous propagation pattern across the PVI line under the high right atrial pacing. The epicardial connection (EC) was defined that the propagation pattern was defined as a centrifugal pattern with the earliest site located around the mid-carina, more than 5 mm far from PVI line.
Results: Carina ablation following PVI was needed more frequently in conventional ablation group than in HP-SD group (38% vs. 17%, P = 0.020). However, there was no statistical difference in EC between HP-SD and conventional ablation groups ［2 of 41 (4.8%) in HP-SD vs. 3 of 52 (5.7%) in conventional, P = 0.852］. This suggests that HP-SD ablation could suppress EG formation more effectively. Among the 5 patients with EC, 4 patients (80%) had HUV adjacent to the earliest activation site at the mid-carina (3 in right and 1 in left). Notably, the EC was eliminated by ablation at the HUV but not at the earliest activation site. During a one-year follow-up, 7 patients experienced AF recurrence. Patients who underwent HP-SD ablation showed lower tendency for recurrence compared to those with conventional ablation (4.8% vs 13.4%, P = 0.126). Notably, no patients who underwent EC ablation in the HP-SD ablation group experienced recurrence, whereas all patients in the conventional ablation group experienced recurrence (0% vs 100%). Among patients requiring carina ablation, 1 of 2 in the HP-SD group and 6 of 7 in the conventional group experienced recurrence (50% vs. 85.7%).
Conclusion: HP-SD ablation was effective to prevent EG and EC, and HUV was useful indicator of epicardial breakthrough site to endocardium.