Ablation procedure
AF ablations were performed by a standardized approach: Patients
underwent the procedure in deep analgosedation with midazolam, fentanyl
and propofol under invasive radial blood pressure monitoring.
Groin-access was achieved using two 6 french and one 12 french venous
sheaths. Diagnostic right ventricle and coronary sinus catheters were
placed in all patients. A single transseptal puncture was guided by
fluoroscopy using Abbott agilis medium curve sheaths and a Abbott BRK
needle, followed by ACT-guided heparin treatment.
All procedures were guided by the Biosense Webster Inc. Carto3 v7
mapping system with univu-fluoroscopy integration. Left atrial
angiograms were recorded under rapid pacing. Left atrial
electro-anatomical reconstruction was done using Biosense Lasso
catheters and the Carto3 V7 confidense module, with low-voltage settings
for substrate mapping as previously described 8,9.
PVI was performed in all patients. Additional lesion sets based on
substrate homogenisation and block-isolation were performed when deemed
necessary as previously described 10. Ablation of the
cavo-tricuspid isthmus was performed when right-atrial flutter was
previously documented or induced during the procedure. All ablations
were performed using the Biosense Webster SmartTouch SurroundFlow
(ST-SF) ablation catheter and the Biosense Webster Smart-Ablate RF
generator. Saline irrigations was performed as recommended by the
manufacturer (<30W 8 ml/s, >30W 15 ml/s).
Ablation lesions were guided by the ablation-index module, with
procedural guidelines and tag-settings previously described and
validated in the CLOSE protocol 4. Briefly, AI targets
of 400 and 550 were used for posterior and anterior lesions,
respectively, with an inter-lesion-distance (ILD) of <6 mm and
VisiTag size of 3 mm. Catheter stability was set to 10 mm, with force
above threshold for >25% of the time, and minimal
stability for 3 seconds. In the control group the AI was reached with
variable power in dependence of the anatomy (posterior and inferior wall
20W, roof and anterior wall 40W). In the HPSD group the AI was reached
with a fixed high power of 50W independently of the anatomical location.
After completion of all ablation sets and documented entrance and exit
blocks, as well as bidirectional block of all additional lines,
inducibility of sustained atrial tachycardia was tested by atrial
high-rate burst and ramp stimulation.
CTI lesions were formed with 40W in both groups. Periprocedural
oesophageal temperature monitoring was not performed.