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.