Methods
Single operator CF and VISITAG™ Module-guided PVI was performed using a previously reported standardised protocol6 in consecutive, unselected adult patients with symptomatic AF undergoing first-time PVI according to current treatment indications.7 Briefly, all procedures were undertaken using GA and IPPV, with respiratory motion “training” undertaken pre-ablation and applied as required to complete the CARTO®3 geometry (V.3, Biosense Webster). Specifically, respiratory motion training was first performed with a LASSO®Nav catheter (Biosense Webster, 2-5-2mm inter-electrode spacing) within the right superior PV. If there was insufficient respiratory motion to trigger its detection, the catheter was placed within the left inferior PV and respiratory motion training re-checked. The tidal volume was never deliberately increased, so respiratory motion detection was negative in some cases. When respiratory motion detection was triggered, RMA (ACCURESP™) remained “off”; i.e. RMA was never applied to automated RF annotation during PVI.
Temperature-controlled RF at 30W (17ml/min irrigation, 48oC) was delivered via a SmartTouch® (Biosense Webster) catheter using Agilis™ NxT sheath (Abbott, St Paul, MN) support during proximal pole CS pacing at 600ms. Filter preferences for automated RF annotation were: Positional stability range 2mm, tag display duration 3s; force-over-time 100% minimum 1g (the latter derived from a previous study8 and designed to ensure on-going RF annotation only in the presence of constant catheter-tissue contact). RF delivery was guided by automated RF annotation, with the preferred site of first RF application at the LAPW opposite each superior PV ~1cm from the PV ostium. The target annotated RF duration at each first-ablated LAPW site, as well as any subsequent “RF ON” sites and at the carina (if ablated) was 15s, whereas ~9-11s was the target for all other sites consecutively annotated during continuous RF delivery. Following the required period of first-site annotated RF delivery, target ITD ≤6mm was achieved predominantly during continuous RF application using deliberate, rapid movement of the catheter tip initiated via the Agilis sheath, aided by the distance measurement tool; point-by-point RF was also applied as necessary. Following completion of circumferential PVI (entrance and exit block), spontaneous recovery of PV conduction was assessed and eliminated during a minimum 20-minute wait; dormant recovery was evaluated and eliminated a minimum of 20 minutes after the last RF. Neither oesophageal luminal temperature monitoring nor post-ablation endoscopic evaluation was employed.
All cases where respiratory motion detection occurred were used to retrospectively assess the effects of RMA on automated RF annotation at the LAPW. VISITAG™ annotated RF and UE morphology change data were retrospectively collected; ablation naïve LAPW sites were examined (i.e. first encirclement during continuous RF delivery, not including touch-up lesions), with annotated RF duration, mean CF, force time integral (FTI) and impedance drop data for each site obtained via the VISITAG™ export function. To examine the effects of RMA, RF data export was performed separately for ACCURESP™ “on” and “off”: at each setting, ITD was determined on-line using the proprietary measurement tool. Retrospective UE analyses were performed using recorded signals (CARTOREPLAY™, Biosense Webster) as previously described6: electrograms were automatically deleted at 12-18 hours after case completion (a CARTO®3 system function), so UE morphology data was only obtained for the ACCURESP™ “off” setting. This work received IRB approval for publication as a retrospective service evaluation. All patients provided written, informed consent.