PLS ablation and conventional ablation
Prior to the procedure, transesophageal echocardiography was performed
to exclude any thrombus formation. Patients were studied under
dexmedetomidine hydrochloride sedation while breathing spontaneously.
Standard electrode catheters were placed in the right ventricular apex
and coronary sinus after which a single transseptal puncture was
performed. Unfractionated heparin was administered in a bolus form
before the transseptal puncture to maintain an activated clotting time
of >350 s.
Mapping and ablation were performed using a NavX system (Abbott,
Chicago, IL) or CARTO3 (Biosense Webster, Diamond Bar, CA, USA) as a
guide after integration of a three-dimensional (3D) model of the anatomy
of the LA and PVs obtained from pre-interventional computed tomography
(CT) or magnetic resonance imaging (MRI). Prior to the ablation, the
circular mapping catheter (Optima, Abbott, Chicago, IL; Carto Lasso,
Biosense Webster, Diamond Bar, CA) and ablation catheter-reconstructed
LA posterior anatomies were aligned with the MRI.
RF alternating current was delivered in a unipolar mode between the
irrigated tip electrode of the ablation catheter (TactiCathTM, Abbott, Chicago, IL; SmartTouch ThermoCool,
Biosense Webster) and an external back-patch electrode. The initial RF
generator setting consisted of maximal RF power of 30 to 35W. All
patients underwent an extensive encircling pulmonary vein isolation. RF
applications were performed in a “point by point” manner. For each RF
application, the target CF was 5 – 30 g, and the target lesion size
index (LSI) or ablation index (AI) was 5.2 or 500,
respectively.9 The RF
application time was routinely limited 10s when ablating the posterior
wall according to the esophageal temperature measured with an esophageal
temperature probe (SensiTherm, Abbott, Chicago, IL). Catheter navigation
was performed with a steerable sheath (Agillis, Abbott, Chicago, IL).
Conventional ablation strategy including the PVI, non-PV foci ablation,
linear ablation, CFAE ablation and low voltage area (LVA) ablation
depended on the operator discussion.
In the PLS group, PVI or PVI plus Box lesion were predefined based on
the LGE-MRI. If the patchy LGE was found at the PV antrum or left atrial
posterior wall, PVI plus Box lesion was attempted. If not, only PVI was
performed. After complete PVI or PVI plus Box was confirmed, RF
application at the patchy LGE site in a point by point manner. Even
though AF could be terminated during the PLS ablation, RF application
continued till it covered the all patchy LGE sites. If AF could convert
to AT during the PLS ablation, mapping and ablation was performed for
the AT termination. AF termination or AT conversion during PLS ablation
were defined as a favorable response positive. If no favorable respond
could be achieved, cardio version was performed. After the procedure, we
performed a stimulation protocol (burst pacing from the CS with 300 ms,
250 ms, and 200 ms for 10s each) to test the inducibility. Holter ECGs
were performed immediately after the procedure and after 6, and 12
months for all patients. If symptoms occurred outside the recording
period, patients were requested to contact our institution or the
referring physician to obtain ECG documentation. AF and AT episodes
lasting >30 s was considered recurrences.