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.