Objectives: The purpose is to evaluate the effect of pulmonary vein angiography (PVA) and spike potential (PSP) mapping guided ultrasound ablation in the pulmonary vein ostium (PVO) to treat focal atrial fibrillation (FAf).

Methods: The criteria of patient enrollment were: 1) paroxysmal FAf ≥6 months, 2) the FAf was refractory to antiarrhythmic agents, 3) without organic heart disease, 4) frequent P'-on-T atrial premature beat (APB) and 5) its induced FAf on Holter. R1 and L1 Swartz sheaths were positioned at PVOs by transseptal approach. PVA was conducted to direct PSP and APB mapping. Target PVO was: 1) clear and stable PSP, 2) earliest APB orientation, 3) PSP driven or triggered FAf. An ultrasound balloon catheter was inserted to ablate target PVO with the parameters of temperature ≥60°C and time 60~120s. The end points were 1) PSP disappeared or its amplitude decreased more than 80%, 2) complete conduction block from PVO to the left atrium, 3) actual ablation temperature ≥50°C and keeping for ≥60s.

Results: Total 24 PVOs (9 left and 9 right superior, 6 left inferior) of 9 patients (M/F 8/1, 57.6±8.3 years old) were ablated. Each PVO was ablated 4.3±1.5 times with actual temperature of 57.2±3.6°C and duration of 96.8±12.5s. The PSP of 8 PVOs (33.3%) disappeared and the amplitude of others was decreased more than 80%. All patients had chest pain during ablation and seven of them were injected opium. There were no complications. All patients had FAf recurred within 48.3±11.7 hours after ablation and previous anti-arrhythmic drugs were then started. During follow-up of 11.8±7.5 month, the frequency of FAf decreased from 5.7±3.9 times per week before ablation to 2.4±0.7 times per week after ablation in 7 patients (77.8%, P<0.05). Another two patients had no FAf recurrence (22.2%).

Conclusions: 1) The end points of APB and PSP disappearance, actual temperature ≥50°C cannot predict immediate and long-term ablation effect of focal FAf. 2) Late remodeling effect of ablated PVO may be one factor to reduce FAf attack. 3) The method of PVA and PSP mapping guided ultrasound ablation in PVO may not be a radical cure to focal FAf.