Electrophysiological study 6 months after Epicor™ high-intensity focused ultrasound atrial fibrillation ablation.

Purpose: Little is presently known about the outcome of atrial lesions performed with high-intensity focused ultrasound (HIFU) for atrial fibrillation ablation. We aimed to assess endocardial atrial lesions 6 months after epicardial HIFU ablation (Epicor(™)) and to evaluate the benefit of a combined ablation approach.

Methods: Thirty patients (21 males, mean age 68 ± 12 years old) undergoing HIFU atrial fibrillation ablation during cardiac surgery were enrolled. Electrophysiological study (EPS) was performed 6 months after HIFU ablation, and endovascular radiofrequency was delivered in case of conduction gaps. Patients were followed up for at least 6 months after the EPS.

Results: At EPS, ten patients (38 %) had achieved complete or near-complete "box" isolation and four (15 %) had no visible lesion. Using this technology, freedom from symptomatic atrial arrhythmia at 6 months was 60 % (n = 18/30) (64 % for paroxysmal and 56 % for persistent subgroups) improving to 81 % (n = 21/26) (90 % for paroxysmal and 73 % for persistent subgroups) at 12 months after a facultative percutaneous endocardial approach was performed. Using an UltraCinch device sized below 10 improved the rate of complete lesion as assessed 6 months after surgery (58 % of complete or near-complete box isolation with UltraCinch device <10 vs 21 % when ≥11; p = 0.05).

Conclusion: Six months after HIFU ablation, only 38 % of the patients had complete or near-complete box isolation, and the recurrence rate of symptomatic atrial arrhythmia was 40 %. The latter was reduced to 19 % 6 months after complementary percutaneous approach.