Introduction Electrical coupling index (ECI) and contact force (CF) have been developed to aid lesion formation during catheter ablation. ECI measures tissue impedance and capacitance whilst CF measures direct contact. The aim was to determine whether the presence of catheter / tissue interaction information, such as ECI and CF, reduce time to achieve bidirectional cavotricuspid isthmus block during atrial flutter (AFL) ablation. Methods Patients with paroxysmal or persistent AFL were randomised to CF visible (range 5-40g), CF not visible, ECI visible (change of 12%) or ECI not visible. Follow-up occurred at 3 and 6 months and included a 7 day ECG recording. The primary endpoint was time to bidirectional cavotricuspid isthmus block. Results 114 patients were randomised, 16 were excluded. Time to bidirectional block was significantly shorter when ECI was visible (median 30.0 mins (IQR 31) to median 10.5mins (IQR 12) p 0.023) versus ECI not visible. There was a trend towards a shorter time to bidirectional block when CF was visible. Higher force was applied when CF was visible (median 9.03g (IQR 7.4) vs. 11.3g (5.5) p 0.017). There was no difference in the acute recurrence of conduction between groups. The complication rate was 2%, AFL recurrence was 1.1% and at 6 month follow-up, 12% had atrial fibrillation. Conclusion The use of tissue contact information during AFL ablation was associated with reduced time taken to achieve bidirectional block when ECI was visible. Contact force data improved contact when visible with a trend towards a reduction in the procedural endpoint. ClinicalTrials.gov trial identifier: NCT02490033.

OBJECTIVES:This study sought to assess the impact of ablation power and catheter irrigation during clinical radiofrequency ablation using impedance drop.BACKGROUND:In preclinical studies, ablation power and catheter irrigation are determinants of ablation efficacy.METHODS:Static 30-s left atrial ablations were delivered in patients undergoing their first atrial fibrillation ablation. Impedance drop during ablation (as a measure of efficacy) was compared using the following: the force time integral (FTI); the FTI-P (a cumulative multiple FTI and ablation power), and ablation index (AI), a weighted algorithm including contact force, power, and duration. Comparison was also made between a conventionally irrigated (SmartTouch [ST]) versus surround flow (STSF) contact force-sensing catheter.RESULTS:We analyzed 1,013 ablations. For both catheters, the Spearman correlation was higher between impedance drop and AI (rho = 0.89 ST, 0.84 STSF) than FTI-P (rho = 0.71 ST, 0.53 STSF) or FTI (rho = 0.77 ST, 0.52 STSF); p < 0.0005 for each. STSF ablations had lower minimum catheter tip temperatures (25°C [interquartile range (IQR): 25°C to 27°C] vs. 35°C [IQR: 34°C to 36°C]; p < 0.005), and lesser impedance drop per FTI or AI (p < 0.005 for both). For STSF, impedance drop plateaued sooner than for ST with respect to FTI (184g.s vs. 463g.s) and AI (370 AI vs. 430 AI).CONCLUSIONS:AI is a more complete ablation descriptor than is FTI or FTI-P, reflected by a stronger correlation with impedance drop. STSF ablations have lower impedance drop per AI or FTI than ST ablations do, suggesting different targets should be used if ablating guided by impedance drop with STSF. With ST, ablation beyond 430 AI provides minimal additional biophysical efficacy, suggesting an upper limit to use for clinical ablation.

Introduction Persistent AF (PeAF) ablation continues to be a challenge, primarily because the mechanism of AF is not clearly defined and even when successfully ablated may evolve into multiple atrial tachycardias or flutters (AT/AFl) during the course of a procedure. Sequential mapping with existing 3D mapping systems can make procedures long and complex. We report the use of a novel simultaneous non-contact ultrasound (US) imaging and mapping system (AcQMap) to characterise of AT/AFl during PeAF ablation. Methods The AcQMap system consists of a basket catheter (48 US transducers, 48 electrodes) which simultaneously acquires 100,000+ US points/min to reconstruct chamber anatomy and 1 50 000 intracardiac unipolar voltage points/s to map cardiac activity. The 3D surface is algorithmically reconstructed from the US point-set with mesh-density comparable to a segmented CT.1 Inverse and forward algorithms are applied on intracardiac voltage to derive and display electrical activation as dipole density™ (DD) and unipolar voltage maps respectively, upon the US-constructed 3D anatomy. Results Data were collected from three patients booked for a first PeAF ablation (2 male, age 48±13 years, time in PerAF 1.7±1.2 years) who also demonstrated AT/AFl either before or during the procedure. All patients had previously failed DCCV and were receiving amiodarone. The AcQMap system was used to measure cardiac voltage, apply its DD algorithm and display electrical activation on the US constructed 3D anatomy to demonstrate the AFl/AT circuit. The circuit was validated using contact mapping and response to ablation. Left atrial (LA) and (right atrial) RA surface acquisition times were 296±20 s and 209±88 s respectively. The maps demonstrated a macro-reentrant circuit in all patients and were used to guide ablation at the isthmus of the circuit. Procedural end point was bidirectional block. Patient 1 presented in typical right AFl (figure 1); Patient 2 presented in SR but with an easily inducible AT around the right upper PV; Patient 3 presented in AF which organised to an AT around the LA posterior wall, and after ablation and termination of this, subsequently to a typical right AFl. Figure 2 shows a Dd-based isochronal plot of the initial AT activation sequence from Patient 3, with breakout at the inferior aspect of the LA posterior wall. All AT/AFl terminated during formation of the ablation line. Maps were then created in SR, and during pacing to demonstrate bidirectional block. Conclusions Real-time US and DD based LA and RA reconstructions using the AcQMap system provide high resolution electro-anatomical maps, allowing rapid and accurate targeting of critical isthmuses for ablation of macro-reentrant AT/AFl. This technique also raises the possibility of mapping AF with more precision to identify areas of interest as potential ablation targets. Reference 1. Heck PM et al. Europace 2015;17(s5):6–9.

Introduction Simulator training can potentially provide high-intensity training in electrophysiology (EP) without compromising patient safety. We assessed the construct validity of a novel EP simulator (ANGIO Mentor; Simbionix) and developed proficiency-based scores for clinical EP simulator training. Methods Two European training centers participated. Participants were grouped on the basis of years of EP experience and (for a subset) subjectively scored clinical catheter manipulation skills. Each participant attempted the simulator's 5 modules 3 times. These modules focus on catheter manipulation in 3-dimensional models, ranging from geometric shapes to fluoroscopic contracting cardiac models, with performance scored by the system on the basis of attainment of preset targets. Using these scores, targets were formulated for basic EP training. Results Twenty-eight participants were included (13 with subjectively scored catheter manipulation). Scores for participants with less than 1-year EP experience (group 1) were significantly lower for each of the attempts at the modules ( P < 0.002). For group 1 only, scores improved with subsequent attempts ( P < 0.005). In 4 of the 5 modules, scores of group 1 were significantly lower than the more experienced groups ( P < 0.0005). Participants with subjectively scored above-average catheter manipulation skills also had higher scores in 4 of the 5 modules ( P < 0.05). Target scores for a proficiency-based training program were generated from the median scores for each module for those with 1-year experience or more. Conclusions Scores attained in the simulator can distinguish those with less than 1-year EP experience and those with above-average catheter manipulation skills. Consequently, target scores have been generated for a proficiency-based training program.

BACKGROUND Contact force (CF) information may improve the safety and efficacy of ablation for paroxysmal atrial fibrillation (PAF).OBJECTIVE The purpose of this study was to assess the impact of CF data on ablation for PAF.METHODS Patients undergoing first-time PAF ablation were randomized at 7 UK centers to ablation with (CF-on) or without (CF-off) CF data available to the operator, using the same ablation catheter and mapping system. An ablation CF of 5-40g was targeted. Pulmonary vein (PV) reconnection was assessed with adenosine at 60 minutes. Follow-up for arrhythmia recurrence was for 1 year with 7-day Holter recordings at 6 and 12 months.RESULTS One hundred seventeen patients were studied (59 CF-on, 58 CF-off). In the CF-on group, a reduction in acute PV reconnection rates (22% vs 32%, P = .03) but no significant difference in 1-year success rates off antiarrhythmic drugs (49% vs 52%, P = .9) was observed. There was no difference in major complication rates: 2 of 59 (3%) CF-on, 3 of 58 (5%) CF-off (P = .7). Procedural and fluoroscopy times were not significantly different (P>.5). Overall mean CFs per ablation were not different between groups (13.4 [9.1-19.6]g CF-on, 13.4 [7.4-22.4]g CF-off, P = .5), but a greater proportion of readings in the CF-on group were in the target range (80% vs 68%, P<.001).CONCLUSION This randomized multicenter study demonstrated that CF data availability was associated with reduced acute PV reconnection but not improved 1-year success rates, procedural and fluoroscopy times, or complication rates. There was a reduction in extremes of CF, above and below the study target range, suggesting greater CF control during ablation. (C) 2016 Heart Rhythm Society. All rights reserved.

The CRYO Versus RF TrialIntroductionCatheter ablation of paroxysmal AF using the Cryoballoon (CRYO) has yielded similar success rates to conventional wide encirclement using radiofrequency catheter ablation (RFCA), but randomized data are lacking. Pilot data suggested a high success rate with a combined approach (COMBINED) using wide encirclement with RFCA followed by 2 CRYO applications to each vein. We compared these 3 strategies in a randomized controlled trial.Methods and ResultsPatients undergoing first time paroxysmal AF ablation were randomized to RFCA, CRYO, or COMBINED. Patients were followed up at 3, 6, and 12 months with 7 days of ambulatory ECG monitoring. Success was defined as freedom from arrhythmia without antiarrhythmic drugs after a single procedure. A total of 237 patients were randomized. Success at 1 year was achieved in 47% in the RFCA group, 67% in the CRYO group, and 76% in the COMBINED group (P < 0.001 for RFCA vs. CRYO, P<0.001 for RFCA vs. COMBINED, and P = 0.220 for CRYO vs. COMBINED). Procedure time was 211 (IQR 174-256) minutes for RFCA compared to 167 (136-202) minutes for CRYO and 278 (243-327) minutes for COMBINED (P < 0.001 for RFCA vs. COMBINED, RFCA vs. CRYO, and CRYO vs. COMBINED groups).ConclusionsPulmonary vein isolation for paroxysmal AF is faster with CRYO and results in a higher single procedure success rate than conventional point by point RFCA. The COMBINED approach was not superior to CRYO alone.

IntroductionContact force (CF) sensing data may facilitate wide area circumferential ablation (WACA). We present data from an interim analysis of the first multicentre randomised controlled trial studying the impact of this data on the ablation of paroxysmal atrial fibrillation (PAF).MethodsAt 7 UK centres, patients undergoing first-time PAF ablation were randomised to ablation with (CF-on) or without CF data (CF-off) available to the operator. Planned recruitment is 120 patients with 1 year follow-up. Using a 3D mapping system and the SmartTouch CF-sensing catheter (Biosense Webster), all patients underwent WACA. Subsequently a 1 h waiting time was observed before assessing acute pulmonary vein (PV) reconnection; if the PV remained isolated, 18 mg adenosine was administered intravenously. The primary end point was acute PV reconnection (spontaneous/adenosine induced). PVs were assessed separately, but cases of a common trunk were taken as one vein. PVs that appeared isolated but were assessed without completing the waiting period were excluded from the acute reconnection analysis. Follow-up is ongoing and 3 month outcomes are reported.Results116 patients have been recruited: age 59 ± 11 years, 57% male, EHRA score 2.7 ± 0.6, AF duration 37 [16–70] months (no significant baseline characteristic differences between groups). There were no differences in procedural parameters (Table 1). There was a significant, 40%, reduction in acute PV reconnection in the CF-on group (Table 1). There were two tamponades and one minor pericardial effusion in the CF-on group, and 1 minor haematoma in the CF-off group. 90 patients (43 CF-off, 47 CF-on) have completed 3 month follow-up: at this point there is no difference in EHRA scores (CF-off 1.6 ± 0.6, CF-on 1.5 ± 0.6, p = 0.8).ConclusionsAddition of CF sensing data had no impact on procedure, fluoroscopy or ablation times, but did reduce acute PV reconnection rates, suggesting more effective ablation application, and consequently more durable PV isolation. Whether this translates to improved long-term success will be assessed on study completion.

BackgroundCatheter-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.MethodsProspective 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.ResultsRRN/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).ConclusionsA 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.

Steerable Sheaths and Contact Force in AF AblationBackgroundIn preclinical studies, catheter contact force (CF) during radiofrequency ablation correlates with the subsequent lesion size. We investigated the impact of steerable sheaths on ablation CF, its consistency, and wide area circumferential ablation (WACA) line reconnection sites.Methods and ResultsFive thousand and sixty‐four ablations were analyzed across 60 patients undergoing first‐time ablation for persistent AF using a CF‐sensing catheter: 19 manual nonsteerable sheath (Manual‐NSS), 11 manual steerable sheath, and 30 robotic steerable sheath (Sensei, Hansen Medical Inc.) procedures were studied. Ablation CFs were higher in the steerable sheath groups for all left atrial ablations and also WACA ablations specifically (P < 0.006), but less consistent per WACA segment (P < 0.005). There were significant differences in the CFs around both WACAs by group: in the left WACA CFs were lower with Manual‐NSS, other than at the anterior–inferior and posterior–superior regions, and lower in the right WACA, other than the anterior–superior region. There was a difference in the proportion of segments chronically reconnecting across groups: Manual‐NSS 26.5%, manual steerable sheath 4.6%, robotic 12% (P < 0.0005). The left atrial appendage/PV ridge and right posterior wall were common sites of reconnection in all groups.ConclusionsSteerable sheaths increased ablation CF; however, there were region‐specific heterogeneities in the extent of increment, with some segments where they failed to increase CF. Steerable sheath use was associated with reduced WACA‐segment reconnection. It may be that the benefits of steerable sheath use in terms of higher CFs could be translated to improved clinical outcomes if regional weaknesses of this technology are taken into account during ablation procedures.

BACKGROUND Catheter ablation of atrial fibrillation (AF) is a physically demanding procedure for the operator, involving radiation exposure, and has limited success rates. Remote robotic navigation (RRN) may offer benefit to the procedure, though only 1 previous small randomized trial has assessed this.OBJECTIVE This study aimed to investigate the impact of RRN on 1-year single-procedure success rates.METHODS RRN was compared to manual ablation in a randomized control trial setting by using an intention-to-treat analysis. RESULTS A total of 157 patients underwent ablation (116/157 (74%) persistent AF; 67/116 (58%) of these long-standing persistent AF). There were no significant differences between the RRN and manual groups with respect to 1-year single-procedure success rates (19/78 (24 /e) and 26/78 (33 /a), respectively; P =.29), acute wide area circumferential ablation reconnection rates, complication rates, or procedure times. On multivariable analysis, fluoroscopy times were significantly shorter in the RRN group. The number of catheter displacements during ablation was lower in the RRN group, as was subjectively assessed operator fatigue. The crossover rate from RRN to manual ablation was 11/78 (14%), mainly secondary to technical problems with the RRN system. A Learning curve was evident for RRN ablation: the fluoroscopy and procedure times were significantly lower after the first 10 cases in an operator's experience.CONCLUSION This randomized trial showed no difference in the success rate for catheter ablation of AF between a RRN and manual approach. The results highlight the learning curve for RRN ablation and suggest that the use of this technology leads to an improvement in fluoroscopy times, catheter stability, and operator fatigue.

Introduction: The addition of contact force (CF) sensing information may facilitate wide area circumferential ablation (WACA). We present data from an interim analysis of the first multicentre randomised controlled trial studying the impact of (CF) sensing information on the ablation of paroxysmal atrial fibrillation (AF). Method: At 7 UK centres, patients undergoing first time paroxysmal AF ablation were randomised to ablation with or without CF data available to the operator. The planned recruitment is 120 patients with 1 year follow up. Using a 3D mapping system and the SmartTouch CF-sensing catheter (Biosense Webster), all patients underwent WACA. Following this, a wait time of 60 minutes was observed before checking for acute electrical pulmonary vein (PV) reconnection. If the PV remained isolated at 60 minutes 18mg adenosine was administered intravenously. The primary end point was acute PV reconnection whether spontaneous or adenosine induced. Each PV was assessed separately, though in cases of a common trunk these were taken as one vein. Where procedures were terminated prematurely for whatever reason, PVs that remained isolated but had not completed the 1 hour waiting period were excluded from the analysis of acute PV reconnection. Follow up is ongoing and outcomes are not reported here. Results: Currently, 91 of 120 patients have been recruited (44 randomised to blinded group, 47 to unblinded group). The mean age was 59±10years, 52.7% male, CHA2DS2VASC 1.5±1.6, duration of AF 36 (6-289) months. There were no significant differences in baseline characteristics between groups. There were no significant differences in the procedural parameters for the procedures as a whole (Table) or for the same parameters for each PV pair separately (p>0.05). There was a significant reduction in the proportion of pulmonary veins that reconnected acutely in the unblinded group, and this was driven by a reduction in left sided reconnections (Table). There were two tamponades and one minor pericardial effusion, all in the unblinded arm (p=0.24). Conclusion: Based on our interim analysis, addition of contact force sensing data had no impact on procedure time, fluoroscopy use, or the amount of ablation used, but did reduce the rate of acute pulmonary vein reconnection suggesting more effective application of ablation lesions. Whether this translates to improved success rates will be assessed on completion of the study.