Repeat ablation procedure
Repeat ablation was recommended for recurrent AF/AT that developed > 3 months after the prior ablation.
Electrophysiological studies and catheter ablation were performed under intravenous sedation with dexmedetomidine. A 6-Fr decapolar electrode was inserted into the coronary sinus while a second 6-Fr decapolar electrode was placed in the right atrium. Following transseptal puncture at the fossa ovalis, two long sheaths were introduced into the left atrium. The operators performed mapping and ablation guided by an electroanatomical mapping system (Rhythmia®, Boston Scientific, Marlborough [Cambridge] MA, USA or Carto3®, Biosense Webster, Diamond Bar CA, USA). When Rhythmia was used, a 64-pole mini-basket catheter (Orion®, Boston Scientific) and an open-irrigated ablation catheter with a 3.5-mm tip (Thermocool Celsius®, Biosense Webster) were used. When CARTO 3 was used, a 20-pole multielectrode mapping catheter arranged in 5 soft radiating spines (Pentaray®, Biosense Webster) and an open-irrigated ablation catheter with a 3.5-mm tip (Thermocool SmartTouch®, Biosense Webster) were used.
Prior to the ablation procedure, we examined the electrical conduction between each PV and the left atrium. If the conduction indicated reconnection, radiofrequency energy was applied at the estimated gap sites. After re-isolation of reconnected PVs, atrial burst pacing (cycle length 200 to 300 ppm for 5 sec) was performed, followed by a high-dose isoproterenol provocation test (infusion of 5, 10, and 20 µg/min isoproterenol for 2 min each) to induce AF or AT. AF-triggering ectopies or frequent ectopies originating from the superior vena cava were eliminated by circumferential superior vena cava isolation. Non-PV AF-triggering ectopies were ablated at the earliest activation site. Spontaneously developing or induced AT was also mapped using the electroanatomical mapping system. Focal ablation targeting the earliest activation site for a centrifugal AT or ablation crossing the reentrant circuit for a macro-reentrant AT was performed.
Empirical ablations such as superior vena cava isolation, and linear ablations of the roof, bottom, lateral mitral isthmus and cavo-tricuspid isthmus were additionally conducted at the discretion of the attending operators. Ablation targeting LVAs, defined as areas with a low bipolar-peak-to-peak voltage < 0.50 mV, was also allowed, irrespective of allocated group.