Comparison of Robotic and Manual Persistent AF Ablation Using Catheter Contact Force Sensing: An International Multicenter Registry Study WAQAS ULLAH, M.B.B.S.,* ROSS J. HUNTER, PH.D.,* SHOUVIK HALDAR, M.B.B.S.,† AILSA MCLEAN, R.N.,* MEHUL DHINOJA, M.B.B.S.,*,‡ SIMON SPORTON, M.D.,*,‡,§ MARK J. EARLEY, M.D.,*,‡,§ FAIZEL LORGAT, PH.D.,¶ TOM WONG, M.D.,† and RICHARD J. SCHILLING, M.D.*,‡,§ From the *Cardiology Research Department, St. Bartholomew’s Hospital, Barts Health NHS Trust, London, UK; †Heart Rhythm Centre, NIHR Cardiovascular Biomedical Research Unit, Royal Brompton & Harefield NHS Foundation Trust & Imperial College London, Institute of Cardiovascular Medicine & Sciences, UK; ‡Cardiology Department, London Independent Hospital, London, UK; §Cardiology Department, London Bridge Hospital, London, UK; and ¶Department of Cardiology, Christiaan Barnard Memorial Hospital, Cape Town, South Africa

Background: Catheter-based contact force sensing (CFS) technology gives detailed information regarding contact between the catheter tip and myocardium. This may result in more effective ablation procedures. The primary objective of this study was comparison of remote robotic navigation (RRN) and Manual CFS ablation. The secondary objective was to compare CFS with non-CFS ablation for both navigation modes. Methods: Prospective registries of consecutive cases undergoing their first ablation for persistent atrial fibrillation (AF) from six hospitals in the United Kingdom and South Africa were analyzed: 50 Manual/CFS and 50 RRN/CFS cases were included. Historical control non-CFS ablation patients were matched by propensity score, giving a total 200 patient cohort. Results: RRN/CFS was associated with improved single procedure 1-year success rates (64% vs 36%, P = 0.01) and shorter fluoroscopy times (41% reduction, P < 0.0005) than Manual/CFS ablation, without any difference in procedure times (P = 0.8). The mean contact force was higher in RRN/CFS than Manual/CFS cases (16 [15–18 g] vs 13 [12–15 g], respectively, P = 0.003). Compared with non-CFS historical controls, CFS cases had higher 1-year success rates for RRN (64% vs 36%, P = 0.01), but not Manual ablation (36% vs 38%, P = 1). Procedure times were reduced for CFS cases (20%, P < 0.005 both navigation modes), as were fluoroscopy times (Manual: 43%, RRN 83%, P < 0.005 for both). There were no differences in rates of major or minor complications for either comparison (P > 0.5). Conclusions: A combination of RRN and CFS is associated with improved success rates at 1 year and fluoroscopy times for persistent AF ablation, compared with Manual ablation and non-CFS RRN ablation. (PACE 2014; 37:1427–1435) atrial fibrillation, catheter ablation, remote robotic navigation, contact force sensing Introduction Increasing catheter contact force (CF) during ablation, while associated with increasing lesion size,1 is also associated with an increasing Conflicts of Interest: Richard J. Schilling: Research funding and research fellow support from Biosense Webster and Hansen Medical. Simon Sporton, Mark J. Earley, and Waqas Ullah: Lecturing honoraria from Biosense Webster. Address for reprints: Richard J. Schilling, M.D., Cardiology Research Department, St. Bartholomew’s Hospital, West Smithfield, London EC1A 7BE, UK. Fax: +442034655771; e-mail: [email protected] Received May 14, 2014; revised June 27, 2014; accepted July 9, 2014. doi: 10.1111/pace.12501

incidence of steam pops and risk of perforation.1,2 Lower CF during ablation has been found to be predictive of sites of pulmonary vein reconnection.3–5 During mapping and ablation of atrial fibrillation (AF), a high degree of variability has been noted in the CFs between different operators and at different sites.6 Therefore, access to CF data may impact the safety and efficacy of clinical ablation procedures, the latter being of importance as success rates from the procedure are around 40% at 1 year, and lower still in patients with persistent AF.7 Remote robotic navigation (RRN—Sensei Robotic Catheter System, Hansen Medical Inc., Mount View, CA, USA) for AF ablation has been found to be associated with a reduction in fluoroscopy times8–11 and more rapid and

©2014 Wiley Periodicals, Inc. PACE, Vol. 37

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greater electrogram attenuation12,13 than Manual ablation, although without a demonstrable impact on success rates to date.8–11 The Sensei platform incorporates a proximal, sheath-based CF measurement system (“Intellisense”). Recently, catheter-based CF sensing (CFS) technology has become available. With the use of CFS catheters in Manual ablation, success rates have been reported as improved by some workers14 but not others,15,16 along with improvements in procedure14–16 and fluoroscopy times.14,15 A similar examination of the impact on RRN ablation has not been made. The primary aim of this study was to compare RRN and Manual ablation using CFS in consecutive, contemporary patients to assess whether the well-described differences between the two navigation modes without CFS were maintained or exaggerated through the use of this technology. A secondary aim was to assess the effect of the addition of CFS on each navigation mode individually by comparison with historical controls where irrigated non-CFS catheters were used. Data from prospective registries from three groups based in six centers in the United Kingdom and South Africa were combined for the analysis. All groups contributing data to the study were based in centers where both CFS and RRN were used and contributed to both the CFS and nonCFS cohorts. Methods This study combined prospective registries of consecutive patients undergoing their first catheter ablation for persistent AF by February 2013 from three groups based in six centers in the United Kingdom and South Africa. Included were 50 patients who had Manual ablations using the Thermocool SmartTouch catheter (Biosense Webster Inc., Diamond Bar, CA, USA), and 50 patients in whom this combination was used with RRN, referred to here as the Manual/CFS and RRN/CFS groups, respectively. The tip electrode of the SmartTouch catheter is mounted on a precision spring permitting a small amount of deflection. By measuring this deflection, the system can accurately calculate the force exerted using the spring’s known mechanical characteristics. The RRN navigation system comprises an inner and outer sheath, each containing a system of pull wires enabling deflection of the sheaths. Through the inner sheath is passed a conventional ablation catheter. The deflection of the catheter follows the deflection of the sheaths. The RRN platform incorporates a CF measurement system, “Intellisense,” which pulses the catheter proximally at 4 Hz and extrapolates


the distal catheter CF by the resistance to motion of the catheter. In RRN cases using CFS in this cohort, Intellisense was not used. The two groups of CFS cases were matched 1:1 to controls from historical cohorts from each contributing group using propensity scores (see “Statistics” section). Ablation Procedure Access was made via the right femoral vein. A decapolar catheter was placed in the coronary sinus. In the manual group, two transseptal punctures were performed using either an Endry’s co-axial needle (Cook Medical, Bloomington, IN, USA) or Brockenbrough needle (St. Jude Medical, St. Paul, MN, USA) according to operator preference. Two sheaths were positioned in the left atrium, for the ablation and circular pulmonary vein catheters. In the RRN group, a 30-cm 14F sheath was inserted into the right femoral vein. The ablation catheter (a SmartTouch catheter or irrigated non-CFS catheter) was then passed through a Hansen Artisan sheath (Hansen Medical Inc.) and the assembly advanced under fluoroscopic guidance to the right atrium, with the catheter leading to reduce the risk of trauma. The transseptal sheath was advanced through the septum in order to dilate it and then withdrawn, following which the ablation catheter and Artisan sheath were passed into the left atrium through the transseptal puncture site either manually or robotically. The pulmonary vein mapping catheter of the operator’s choice was then introduced into the left atrium through either the same or a separate transseptal puncture, depending on the preference of the operator. Wide area circumferential ablation (WACA) was then performed to encircle the left- and right-sided pulmonary veins as pairs with the aim of producing entry and exit block (the latter assessed subsequently in sinus rhythm). A cavotricuspid isthmus line was added only in patients with a history of typical atrial flutter: beyond this, lines of block and fractionated activity were ablated according to the discretion of the operator. Fractionated electrograms were targeted throughout the left then right atria (as previously described17 ) until all were abolished or sinus rhythm was restored and, if patients remained in AF, linear lesions were added at the mitral isthmus and roof. If at any point AF organized into atrial tachycardia (AT), this was mapped and ablated. If sinus rhythm was not restored following these lesions, the patient was electrically cardioverted. The pulmonary veins were rechecked at the end of the case in sinus rhythm and reisolated where necessary. Linear lesions were checked and further lesions delivered

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where necessary to achieve block. Whether the ablations were performed as “point-to-point” or “drag” ablations was dependent on the operator, as were the ablation temperature and power settings. Whether using Intellisense or CFS, the CF data were available to the operators, with ablation performed at a CF of 5–40 g. The procedure time for this study was the time from the local anesthetic being administered to the end of the case, when the catheters were removed from the patient. The time taken to perform each WACA was determined from the logs of the 3D mapping system and electrogram recording system used, and determined from when circumferential ablation had been completed and entrance block was demonstrated. Severity was assigned to complications on the basis of current guidelines.18 Postprocedure, a 3-month blanking period was used with episodes of AT during this time not considered as recurrence. Those patients without a permanent pacemaker or documented arrhythmia had ambulatory electrocardiogram monitoring performed with at least one 48-hour Holter monitor by 6 months, and further monitoring dictated by the presence or absence of symptoms. Success was defined as freedom from documented atrial tachyarrhythmia whether symptomatic or asymptomatic, lasting ࣙ30 seconds, off all antiarrhythmic medication18 at 1-year postablation, after a single ablation procedure. In the CFS cohort, in the subset of patients where the CF data were available to the researchers, CF data were analyzed using custom written scripts in Matlab (MathWorks, Natick, MA, USA). The mean ablation CF was determined by combining all the 20-Hz sampled CF data for each individual ablation into a single ablation and then taking an average of this combined ablation. The proportion of the ablation in a case performed at ࣙ5 g or ࣙ10 g was also determined from this combined ablation. The force time integral (FTI) was given by the area under the force-time curve for each individual ablation in a case, and the values were summated to give the total FTI for the case. Statistics The CFS groups were matched 1:1 without replacement to historical controls using propensity scores based on the duration of persistent AF, patient gender and presence of severe left ventricular systolic dysfunction,19 the left atrial size,20 and contributing physician group. Matching was performed in SPSS 20 (IBM Corp., Armonk, NY, USA) with a fuzzy matching algorithm to match propensity scores using a match tolerance of 0.1. The groups were compared

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using parametric or nonparametric testing based on the distribution of the data. Matched data were compared using either a paired t-test, Wilcoxon signed rank test, or, if categorical data, McNemar’s test, and survival curves for matched data compared using a stratified log rank test.21,22 Data that were not paired were compared using a t-test, Mann-Whitney U test, or, if categorical data, a Fisher’s exact test, and survival curves were compared using the log rank test. Data are presented as mean ± standard deviation or median (interquartile range). A P value 0.09 for each, Fig. 1). RRN/CFS was associated with significantly lower fluoroscopy times (41% shorter) compared with Manual/CFS (Figure 2). There was no significant difference in the fluoroscopy dose though (Manual/CFS: 1,850 [1,035–3,077] cGy·cm2 , RRN/CFS: 1,022 [290–3,438] cGy·cm2 , P = 0.08). There were no significant differences in the complication rates (Table II). CF data were available for a subset of the CFS patient cohort (43 patients: 21 RRN, 22 Manual). Compared with Manual/CFS, the RRN/CFS group ablations were at a higher mean CF and FTI, and with a higher proportion of ablation (ࣙ10 g of CF), but without any significant increase in the total ablation time (Table III). The single-procedure success rate over 12 months of follow-up was significantly better for RRN/CFS than Manual/CFS ablation (P = 0.03; Fig. 3). At 12 months, the success rates were 36% (18/50) for Manual/CFS and 64% (32/50) for RRN/CFS (P = 0.009). Of those with an atrial tachyarrhythmia by 12 months, in 65%

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November 2014 46 54 24

50 41 (82%) 63 [53–70] 12 [6–18] 4.4 ± 0.6 22 7 2 5 2 1.5 ± 1.3 100 62 50 46

50 44 (88%) 59 [53–65] 10 [6–18] 4.3 ± 0.7 15 6 3 2 3 1.1 ± 1.0 100


0.08 0.8 0.04

0.6 0.2 1 0.2 0.2 1 1 0.4 1 0.1 1

P Value (CFS Groups)

40 66 22

50 39 (78%) 62 [55–65] 12 [6–18] 4.4 ± 0.6 14 4 5 4 2 1.4 ± 1.3 20

Manual No CFS

0.7 0.3 1

0.7 0.8 0.9 0.8 0.2 0.5 0.5 1 1 0.5

Comparison of robotic and manual persistent AF ablation using catheter contact force sensing: an international multicenter registry study.

Catheter-based contact force sensing (CFS) technology gives detailed information regarding contact between the catheter tip and myocardium. This may r...
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