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Implantable loop recorders (ILRs) are effective in achieving symptom-rhythm correlation. Data on the diagnostic yield of ILRs, on nurse-led syncope clinics, and on nurse-led ILR implants are limited.We evaluated the safety and efficacy of our nurse-led syncope clinic and nurse-led ILR implants.A retrospective study of all consecutive patients undergoing nurse-led ILR implantations was performed between April 2016 and April 2018. Patients were referred from both nurse-led and physician-led clinics. Data were collected on baseline demographic characteristics, referral source, symptom-rhythm correlation, ILR findings, and subsequent changes to management. All ILRs were enrolled into remote monitoring with automatic arrhythmia detection, and all immediate (≤24 hours) ILR implant complications were recorded. Comparisons were made between nurse-led and physician-led clinics and subsequent outcomes.A total of 432 patients with an ILR were identified: 164 (38%) from nurse-led and 268 (62%) from physician-led clinics; 200 (46%) were women (mean age 66.5 ± 18.2 years; mean follow-up duration 28.9 ± 9.5 months). Primary ILR indications were syncope (n = 251 [58%]), presyncope (n = 33 [7%]), palpitation (n = 39 [9%]), cryptogenic stroke (n = 78 [18%]), and other reasons (n = 31 [7%]). No immediate ILR implant complications occurred. Overall, 156 patients (36%) had a change in management as a direct result of ILR findings, with no overall differences between nurse-led and physician-led clinics (35% vs 36%; P = .7). More patients had newly diagnosed atrial fibrillation in physician-led clinics (15% vs 7%; P = .01), and more patients had pacemaker implants for bradycardia in nurse-led clinics (23% vs 13%; P.01).Nurse-led ILR implantation was safe and effective. Nurse-led syncope clinics achieved good symptom-rhythm correlation with resultant significant changes to management in comparison to physician-led clinics. Larger prospective studies are needed to evaluate their longer-term impact.

Background Transvenous lead extraction (TLE) for implantable cardiac‐devices is traditionally performed under general anesthesia (GA). This can lead to greater risk of exposure to COVID‐19, longer recovery‐times and increased procedural‐costs. We report the feasibility/safety of TLE using conscious‐sedation alone with immediate GA/cardiac‐surgery back‐up if needed. Methods Retrospective case‐series of consecutive TLEs performed using conscious‐sedation alone between March 2016 and December 2019. All were performed in the electrophysiology‐laboratory using intravenous Fentanyl, Midazolam/Diazepam with a stepwise approach using locking‐stylets/cutting‐sheaths, including mechanical‐sheaths. Baseline patient‐characteristics, procedural‐details and TLE outcomes (including procedure‐related complications/death) were recorded. Results A total of 130 leads were targeted in 54 patients, mean age ± SD 74.6 ± 11.8years, 47(87%) males; dual‐chamber pacemakers (n = 26; 48%), cardiac resynchronization therapy‐defibrillators (n = 17; 31%) and defibrillators (n = 8; 15%) were commonest extracted devices. Mean ± SD/median (range) lead‐dwell times were 11.0 ± 8.8/8.3 (0.3‐37) years, respectively. Extraction indications included systemic infection (n = 23; 43%) and lead/pulse‐generator erosion (n = 27; 50%); mean 2.1 ± 2.0 leads were removed per procedure/mean procedure‐time was 100 ± 54 min. Local anesthetic (LA) was used for all (mean‐dose: 33 ± 8 ml 1% lidocaine), IV drug‐doses used (mean ± SD) were: midazolam: 3.95 ± 2.44 mg, diazepam: 4.69 ± 0.89 mg and fentanyl: 57 ± 40 µg. Complete lead‐extraction was achieved in 110 (85%) leads, partial lead‐extraction (, TLE undertaken using LA/conscious‐sedation was safe/feasible in our series and associated with good clinical outcome/low procedural complications. Reduced risk of aerosolisation of Covid‐19 and quicker patient recovery/reduced anesthetic risk are potential benefits that warrant further study.

Background The DiamondTemp ablation (DTA) catheter system delivers high power, open-irrigated, temperature-controlled radiofrequency (RF) ablation. This novel ablation system has not been previously used for ventricular tachycardia (VT) ablation. Objective Feasibility of using the DTA catheter system for VT ablation in ischaemic cardiomyopathy (ICM) patients. Method Ten ICM patients with optimal anti-arrhythmic drug therapy and implantable cardiac defibrillators (ICD) were recruited. VT inducibility testing was performed at the end of the procedure. ICD data for device detected VT episodes and device treated VT episodes were collected for 6-months pre- and post-ablation. Results Substrate analysis demonstrated reductions in the borderzone area of 4.4 cm2 (p = 0.026) and late potential area of 3.5 cm2 (p = 0.0449) post-ablation, with reductions in the mean bipolar and unipolar voltages of the ablation target areas (0.14 mV (p = 0.0007); 0.59 mV (p = 0.0072) respectively). Complete procedural success was achieved in 9 procedures. Post-ablation VT inducibility testing was not performed in 1 procedure due to a steam pop complication resulting in pericardial tamponade requiring drainage. Mean follow-up of 214 ± 33 days revealed an 88% reduction in total VT episodes (n = 266 median 16 [IQR 3–57] to n = 33 median 0; p = 0.0164) and 77% reduction in ICD therapies (n = 128 median 5 [IQR 2–15] to n = 30 median 0; p = 0.0181). Conclusion The DTA system resulted in adequate lesion characteristics with effective substrate modification, acute procedural success and improved outcomes at intermediate-term follow-up. Randomised controlled trials are required to compare the performance of the DTA system against conventional ablation catheters.

OBJECTIVES To study how left atrial appendage electrical isolation (LAAEI) impacts atrial dominant frequency (DF) in patients with long-standing persistent atrial fibrillation (LSPAF). BACKGROUND LAAEI is associated with a high probability of freedom from atrial fibrillation (AF) and spectral analysis may identify high-frequency sources. How LAAEI impacts the AF dynamics and the subgroup of LSPAF patients in whom LAAEI would be most beneficial, is unclear. METHODS Twenty patients with LSPAF were included in the study. Fast Fourier transforms (FFT) were performed on atrial electrograms recorded from 13 sites in the LA and RA. The highest peak frequency was defined as DF. RESULTS There was no significant difference in DF between atrial sites except for at the superior vena cava which had the lowest DF at baseline. Stepwise ablation consisting of circumferential pulmonary vein isolation and a linear ablation set of mitral isthmus and roof significantly reduced the DF within the coronary sinus (CS) (5.93 ± 0.98 Hz vs. 5.09 ± 0.72 Hz, p < .05) and the LA posterior wall (LApos) (6.26 ± 0.92 Hz vs. 5.43 ± 0.98 Hz, p < .01). LAAEI preferentially further decreased the DF at the LApos (p < .01), but not at the CS. In cases where there was

Background Catheter ablation for complex left-atrial arrhythmia is increasing worldwide with many centres admitting patients overnight. Same-day procedures using conscious sedation carry significant benefits to patients/healthcare providers but data are limited. We evaluated the safety and cost-effectiveness of same-day complex left-atrial arrhythmia ablation. Method Multi-centre retrospective cohort study of all consecutive complex elective left-atrial ablation procedures performed between January 2011 and December 2019. Data were collected on planned same-day discharge versus overnight stay, baseline parameters, procedure details/success, ablation technology, post-operative complications, unplanned overnight admissions/outcomes at 4-months and mortality up to April 2020. A cost analysis of potential savings was also performed. Results A total of 967 consecutive patients underwent complex left-ablation using radiofrequency (point-by-point ablation aided by 3D-mapping or PVAC catheter ablation with fluoroscopic screening) or cryoballoon-ablation (mean age: 60.9 ± 11.6 years, range 23-83 yrs., 572 [59%] females). The majority of patients had isolation of pulmonary veins alone (n = 846, 87%) and most using conscious-sedation alone (n = 921, 95%). Of the total cohort, 414 (43%) had planned same-day procedure with 35 (8%) admitted overnight due to major (n = 5) or minor (n = 30) complications. Overall acute procedural success-rate was 96% (n = 932). Complications in planned overnight-stay/same-day cohorts were low. At 4-month follow-up there were 62 (6.4%) readmissions (femoral haematomas, palpitation, other reasons); there were 3 deaths at mean follow-up of 42.0 ± 27.6 months, none related to the procedure. Overnight stay costs £350; the same-day ablation policy over this period would have saved £310,450. Conclusions Same-day complex left-atrial catheter ablation using conscious sedation is safe and cost-effective with significant benefits for patients and healthcare providers. This is especially important in the current financial climate and Covid-19 pandemic., Highlights • We have previously reported same-day standard catheter ablation is safe, feasible and cost-effective. Data on same-day complex left-atrial ablation are limited. • Our multi-centre cohort study of 967 consecutive elective complex left-atrial ablation procedures between January 2011 and December 2019 revealed same-day ablations using conscious sedation were safe and associated with very few complications and could have significant benefits to patients and cost-savings for healthcare providers worldwide. • Same-day complex left-atrial ablation procedures can be performed safely without the need for overnight-stay. This has major implications for both patients and healthcare providers, especially given the current financial challenges and Covid-19 pandemic.

Background Postural orthostatic tachycardia syndrome (POTS) is an autonomic nervous system disorder causing an abnormal cardiovascular response to upright posture. It affects around 0.2% of the population, most commonly women aged 13 to 50 years. POTS can be debilitating; prolonged episodes of pre-syncope and fatigue can severely affect activities of daily living and health-related quality of life (HRQoL). Medical treatment is limited and not supported by randomised controlled trial (RCT) evidence. Lifestyle interventions are first-line treatment, including increased fluid and salt intake, compression tights and isometric counter-pressure manoeuvres to prevent fainting. Observational studies and small RCTs suggest exercise training may improve symptoms and HRQoL in POTS, but evidence quality is low. Methods Sixty-two people (aged 18–40 years) with a confirmed diagnosis of POTS will be invited to enrol on a feasibility RCT with embedded qualitative study. The primary outcome will be feasibility; process-related measures will include the number of people eligible, recruited, randomised and withdrawn, along with indicators of exercise programme adherence and acceptability. Secondary physiological, clinical and health-related outcomes including sub-maximal recumbent bike exercise test, active stand test and HRQoL will be measured at 4 and 7 months post-randomisation by researchers blinded to treatment allocation. The PostUraL tachycardia Syndrome Exercise (PULSE) intervention consists of (1) individual assessment; (2) 12-week, once to twice-weekly, supervised out-patient exercise training; (3) behavioural and motivational support; and (4) guided lifestyle physical activity. The control intervention will be best-practice usual care with a single 30-min, one-to-one practitioner appointment, and general advice on safe and effective physical activity. For the embedded qualitative study, participants (n = 10 intervention, n = 10 control) will be interviewed at baseline and 4 months post-randomisation to assess acceptability and the feasibility of progressing to a definitive trial. Discussion There is very little high-quality research investigating exercise rehabilitation for people with POTS. The PULSE study will be the first randomised trial to assess the feasibility of conducting a definitive multicentre RCT testing supervised exercise rehabilitation with behavioural and motivational support, compared to best-practice usual care, for people with POTS. Trial registration ISRCTN45323485 registered on 7 April 2020.

Background Circulatory collapse during/post-pulmonary vein (PV) isolation by cryo-balloon ablation is a Cardiology emergency that has multiple potential causes and requires a methodical investigative approach. Some of the complications that can arise include cardiac tamponade, bleeding/vascular injury, anaphylaxis, Addisonian crisis, acute pulmonary embolism, acute PV stenosis, oesophageal injury, and vagal reaction. Case summary Here, we present a case of a 76-year-old lady who developed profound circulatory collapse during an elective pulmonary vein isolation by cryo-balloon ablation for symptomatic paroxysmal atrial fibrillation (AF). Cardiac tamponade, bleeding/vascular injury, and other less common causes were excluded. She only responded transiently to fluid resuscitation and developed intermittent bradyarrhythmias and hypotension which responded to isoprenaline. She was discharged home at Day 3 post-AF ablation after remaining well and continued to do so at follow-up. Discussion Circulatory collapse during/post-PV cryo-balloon ablation is a Cardiology emergency that has multiple potential causes. The ganglionate plexi form part of the cardiac intrinsic autonomic nervous system (ANS) and are located close to the left atrial–PV junctions. The presence of vagal response has been observed to be a marker of ANS modulation although its significance on the long-term outcome post-ablation has yet to be elucidated. The true cause of our patient’s profound circulatory collapse is uncertain but a vital learning point in this case is the systematic exclusion of common and potentially life-threatening complications following AF ablation. A persistent vagal reaction secondary to PV cryo-balloon ablation can usually be managed with supportive medical therapy as demonstrated in our case.

Catheter ablation is an accepted therapeutic option for paroxysmal atrial fibrillation (AF), but its role is less certain in patients with persistent AF.1 The difference in response to pulmonary vein (PV) isolation (PVI) between paroxysmal and persistent forms of AF may arise because of triggers from non-PV sites or alterations in atrial substrate favoring maintenance of AF that are unaffected by PVI alone.2 In support of this statement, adjunctive ablation of certain sites (including the superior vena cava, ligament of Marshall [LOM], crista terminalis, coronary sinus [CS], posterior wall of the left atrium [LA], and left atrial appendage [LAA]) as well as more widespread ablation aimed at modifying substrate has been shown to improve the success of catheter ablation of persistent AF. In the case of the LAA, the BELIEF study (Effect of Empirical Left Atrial Appendage Isolation on Long-term Procedure Outcome in Patients With Persistent or Long-standing Persistent Atrial Fibrillation Undergoing Catheter Ablation)3 recently showed that in patients with long-standing persistent AF, empirical electrical isolation of the LAA together with extensive atrial ablation markedly improved freedom from AF at 1 year compared to an extensive atrial ablation strategy alone. However, electrical isolation of the LAA can be challenging and is sometimes impossible to achieve. This may be partly because the electrical connections of the LAA are not completely understood. Here we report 2 patients showing that the CS can be an important electrical conduit to the LAA.

Background Catheter ablation (CA) outcomes for long-standing persistent atrial fibrillation (LSPAF) remain suboptimal. Thoracoscopic surgical ablation (SA) provides an alternative approach in this difficult to treat cohort. Objective To compare electrophysiological (EP) guided thoracoscopic SA with percutaneous CA as the first-line strategy in the treatment of LSPAF. Methods Fifty-one patients with de novo symptomatic LSPAF were recruited. Twenty-six patients underwent electrophysiologically guided thoracoscopic SA. Conduction block was tested for all lesions intraoperatively by an independent electrophysiologist. In the CA group, 25 consecutive patients underwent stepwise left atrial (LA) ablation. The primary end point was single-procedure freedom from atrial fibrillation (AF) and atrial tachycardia (AT) lasting >30 seconds without antiarrhythmic drugs at 12 months. Results Single- and multiprocedure freedom from AF/AT was higher in the SA group than in the CA group: 19 of 26 patients (73%) vs 8 of 25 patients (32%) (P = .003) and 20 of 26 patients (77%) vs 15 of 25 patients (60%) (P = .19), respectively. Testing of the SA lesion set by an electrophysiologist increased the success rate in achieving acute conduction block by 19%. In the SA group, complications were experienced by 7 of 26 patients (27%) vs 2 of 25 patients (8%) in the CA group (P = .07). Conclusion In LSPAF, meticulous electrophysiologically guided thoracoscopic SA as a first-line strategy may provide excellent single-procedure success rates as compared with those of CA, but there is an increased up-front risk of nonfatal complications.

Aims Characterizing the differences in substrate and clinical outcome between heart failure (HF) and non-heart failure (non-HF) patients undergoing persistent atrial fibrillation (AF) ablation. Methods and results Using complex fractionated electrograms (CFE) as a surrogate marker of substrate complexity, we compared the bi-atrial substrate in patients with persistent AF with and without HF, at baseline and after ablation, to determine its impact on clinical outcome. In this retrospective analysis of two prospective studies, 60 patients underwent de-novo step-wise left atrial (LA) ablation, 30 with normal left ventricular ejection fraction (LVEF) ≥ 50% (non-HF group) and 30 with LVEF ≤ 35% (HF group). Multiple high-density bi-atrial CFE maps were acquired along with AF cycle length (AFCL) at each procedural stage. Change in bi-atrial CFE areas, AFCL and outcome data were then compared. In the non-HF group, higher CFE-areas were found at baseline and at each step of the procedure in the LA. In both LA and the right atrium (RA), baseline and final CFE area were also higher in the non-HF group. Single procedure, arrhythmia-free survival at 1 year was higher in the HF group compared with the non-HF group (72% vs. 43%, log rank P = 0.04). Final total bi-atrial CFE area was an independent predictor of arrhythmia recurrence. Conclusions CFE represents an important surrogate marker of atrial substrate complexity. The atrial substrate in persistent AF differs between HF and non-HF with the latter representing a more complex ‘primary’ bi-atrial myopathy. LA focussed ablation results in more extensive substrate modification in HF and better clinical outcomes as compared with non-HF.

Defining diastolic slow-conduction channels within the borderzone (BZ) of scar-dependent re-entrant ventricular tachycardia (VT) is key for effective mapping and ablation strategies. Understanding wavefront propagation is driving advances in high-density (HD) mapping. The newly developed Advisor™ HD Grid Mapping Catheter (HD GRID) has equidistant spacing of 16, 1 mm electrodes in a 4 × 4 3 mm interspaced arrangement allowing bipolar recordings along and uniquely across the splines (orthogonal vector) to facilitate substrate mapping in a WAVE configuration (WAVE). The purpose of this study was to determine the relative importance of the WAVE configuration compared to the STANDARD linear-only bipolar configuration (STANDARD) in defining VT substrate. Thirteen patients underwent VT ablation at our institution. In all cases, a substrate map was constructed with the HD GRID in the WAVE configuration (conWAVE) to guide ablation strategy. At the end of the procedure, the voltage map was remapped in the STANDARD configuration (conSTANDARD) using the turbo-map function. Detailed post-hoc analysis of the WAVE and STANDARD maps was performed blinded to the configuration. Quantification of total scar area, BZ and dense scar area with assessment of conduction channels (CC) was performed. The substrate maps conSTANDARD vs conWAVE showed statistically significant differences in the total scar area (56 ± 32 cm2 vs 51 ± 30 cm2; p = 0.035), dense scar area (36 ± 25 cm2 vs 29 ± 22 cm2; p = 0.002) and number of CC (3.3 ± 1.6 vs 4.8 ± 2.5; p = 0.026). conWAVE collected more points than the conSTANDARD settings (p = 0.001); however, it used fewer points in map construction (p = 0.023). The multipolar Advisor™ HD Grid Mapping Catheter in conWAVE provides more efficient point acquisition and greater VT substrate definition of the borderzone particularly at the low-voltage range compared to conSTANDARD. This greater resolution within the low-voltage range facilitated CC definition and quantification within the scar, which is essential in guiding the ablation strategy.

Background and aims Syncope guidelines recommend Implantable loop recorders (ILR) to aid symptom-rhythm correlation. Arrhythmia Nurse Specialists (ANS) are important in assessment of these patients. Their effectiveness at risk stratification is unknown. ESC 2018 Syncope guidelines recommend more research. Our aim was to evaluate the diagnostic yield of all consecutive ILR implants over a 2-year period and compare ILR-guided management changes between ANS and clinicians. Methods Retrospective study of consecutive patients undergoing ILR implant between April 2016-April 2018, including baseline patient demographics, referral source and management changes made by ILR findings. Results 305 ILR patients were identified: median age 71 yrs (interquartile range 52–81), 45% female, median follow-up time 15months. Referrals were from general cardiology (GC)=98 (32%), electrophysiology (EP)=105 (34%) and ANS-led syncope clinic=102 (34%). Indications were syncope=203 (65.9%), palpitation=21 (6.9%), pre-syncope=16 (5.2%), cryptogenic stroke=35 (11.5%) and other reasons 7 (8.9%) (falls, channelopathies). Overall, 102 (34.0%) experienced arrhythmias detected on ILR that resulted in a change of management including: pacemaker implant=49 (16.1%), complex-device implant=7 (2.3%) and AF=28 (9.2%), SVT=14 (4.6%), VT=1 (0.3%). ANS referrals resulted in greater trend towards change of management (38.2%) of patients compared with GC (32.7%) and EP (31.4%) (p=0.593 nurse vs. consultant). For those needing pacing, 24 were from ANS referrals compared to 25 for clinicians (23.5% vs 18.3% respectively, p=0.012). Median time to developing a pacing indication was 2.6 months for ANS and 4.1 months for clinicians; 25 had pacing indication within 3 months of ILR insertion. Overall, an ILR had a diagnostic yield of 34.1% (n= 104) (table 1). Conclusion The diagnostic yield of ILR insertion was 34%. ANS referrals trended towards greater diagnostic yield compared with clinicians and significantly more pacemaker indications. Our data suggest ANS patient selection for ILRs are at least comparable to clinicians. Conflict of Interest None

Background Atrial tachycardia ( AT ) is common in patients with adult congenital heart disease and is challenging to map and ablate. We used ultra‐high‐density mapping to characterize the AT mechanism and investigate whether substrate characteristics are related to ablation outcomes. Methods and Results A total of 50 AT s were mapped with ultra‐high‐density mapping in 23 procedures. Patients were followed up for up to 12 months. Procedures were classified to group A if there was 1 single AT induced (n=12) and group B if there were ≥2 AT s induced (n=11 procedures). AT mechanism per procedure was macro re‐entry (n=10) and localized re‐entry (n=2) in group A and multiple focal (n=6) or multiple macro re‐entry (n=5) in group B. Procedure duration, low voltage area (0.05–0.5 mV), and low voltage area indexed for volume were higher in group B (159 [147–180] versus 412 [352–420] minutes, P 2 , P =0.014 and 0.17 [0.12–0.21] versus 0.26 [0.23–0.27] cm 2 /mL, P =0.024 accordingly). Dense scar (P =0.009 and 11.3, CI 9.8–12.7 versus 4.9, CI 2.2–7.6 months, log rank P =0.004). Indexed low voltage area ≥0.24 cm 2 /mL could predict recurrence with 100% sensitivity and 77% specificity (area under the curve 0.923, P =0.007). Conclusions Larger low voltage area but not dense scar is associated with the induction of multiple focal or re‐entry AT s, which are subsequently associated with longer procedure duration and worse acute and midterm clinical outcomes.

BackgroundVentricular tachycardia (VT) is associated with increased morbidity and mortality. There is growing evidence for the effectiveness of catheter ablation in improving outcomes in patients with recurrent VT. Consequently the threshold for referral for VT ablation has fallen over recent years, resulting in increased number of procedures.ObjectiveTo evaluate the effectiveness and safety of VT ablation in a real-world tertiary centre setting.MethodsThis is a prospective analysis of all VT ablation cases performed at University Hospital Coventry. Follow-up data were obtained from review of electronic medical records and patient interview. The primary endpoint for normal heart VT was death, cardiovascular hospitalisation and VT recurrence, and for structural heart VT was arrhythmic death, VT storm (>3 episodes within 24 hours) or appropriate shock.ResultsForty-seven patients underwent 53 procedures from January 2012 to January 2018. The mean age ±SD was 57±15 years, 68% were male, 81% were Caucasian and 66% were elective cases. The aetiology of VT included normal heart (49%), ischaemic cardiomyopathy (ICM, 36%), dilated cardiomyopathy (9%), hypertrophic cardiomyopathy (4%) and valvular heart disease (2%). Procedural success occurred in 83%, with six major complications. After a median follow-up of 231 days (lower quartile 133, upper quartile 631), the primary outcome occurred in 28% of patients. There were two non-arrhythmic deaths (4%). At a median follow-up of 193 days (129–468), the primary outcome occurred in 19% of patients with ICM, while VT storm/appropriate shocks occurred in three patients (17%).ConclusionsOur real-world registry confirms that VT ablation is safe, and is associated with high acute procedural success and long-term outcomes comparable with randomised controlled studies.

Objectives This study aimed at assessing the feasibility and long-term efficacy of left atrial appendage occlusion (LAAO) in a “real world” setting. Background Although LAAO has recently emerged as an alternative to oral anticoagulants in patients with atrial fibrillation for the prevention of thromboembolic stroke, “real world” data about the procedure with different devices are lacking. Methods Eight centers in the United Kingdom contributed to a retrospective registry for LAAO procedures undertaken between July 2009 and November 2014. Results A total of 371 patients (72.9 ± 8.3 years old, 88.9% males) were enrolled. The overall procedure success was 92.5%, with major events in 3.5% of cases. The device choice was Watchman in 63% of cases, Amplatzer Cardiac Plug in 34.7%, Lariat in 1.7%, and Coherex WaveCrest in 0.6%. A significant improvement in procedure success (from 89.2% to 95.7%; P = 0.018) and reduction of acute major complications (from 6.5% to 0.5%; P = 0.001) were observed between procedures in the first and the second half of the recruitment time. An annual 90.1% relative risk reduction (RRR) for ischemic stroke, an 87.2% thromboembolic events RRR, and a 92.9% major bleeding RRR were observed, if compared with the predicted annual risks based on CHADS2, CHA2DS2-Vasc, and HAS-BLED scores, respectively, over a follow-up period of 24.7 ± 16.07 months. Conclusions LAAO can be performed safely in a real world setting with good implant success rates and procedural outcomes. The long-term benefits of the procedure are reassuring in terms of both ischemic events and avoidance of severe bleeding associated with anticoagulation in this patient group. © 2016 Wiley Periodicals, Inc.

Aims The aim of this study was to analyse randomized controlled study and real-world outcomes of patients with non-valvular atrial fibrillation (NVAF) undergoing left atrial appendage closure (LAAC) with the Watchman device and to compare costs with available antithrombotic therapies. Methods and results Registry data of LAAC from two centres were prospectively collected from 110 patients with NVAF at risk of stroke, suitable and unsuitable for long-term anticoagulation (age 71.3 ± 9.2 years, CHADS2 2.8 ± 1.2, CHA2DS2-VASc 4.5 ± 1.6, and HAS-BLED 3.8 ± 1.1). Outcomes from PROTECT AF and registry study LAAC were compared with warfarin, dabigatran, rivaroxaban, apixaban, aspirin, and no treatment using a network meta-analysis. Costs were estimated over a 10-year horizon. Uncertainty was assessed using sensitivity analyses. The procedural success rate was 92% (103/112). Follow-up was 24.1 ± 4.6 months, during which annual rates of stroke, major bleeding, and all-cause mortality were 0.9% (2/223 patient-years), 0.9% (2/223 patient-years), and 1.8% (4/223 patient-years), respectively. Anticoagulant therapy was successfully stopped in 91.2% (93/102) of implanted patients by 12 months. Registry study LAAC stroke and major bleeding rates were significantly lower than PROTECT AF results: mean absolute difference of stroke, 0.89% ( P = 0.02) and major bleeding, 5.48% ( P < 0.001). Left atrial appendage closure achieved cost parity between 4.9 years vs. dabigatran 110 mg and 8.4 years vs. warfarin. At 10 years, LAAC was cost-saving against all therapies (range £1162–£7194). Conclusion Left atrial appendage closure in NVAF in a real-world setting may result in lower stroke and major bleeding rates than reported in LAAC clinical trials. Left atrial appendage closure in both settings achieves cost parity in a relatively short period of time and may offer substantial savings compared with current therapies. Savings are most pronounced among higher risk patients and those unsuitable for anticoagulation.

More advanced atrial fibrillation (AF) is associated with lower success rates after pulmonary vein isolation (PVI), and the optimal ablation strategy is uncertain.To assess the impact of additional linear ablation (lines) compared to PVI alone.In this multicenter randomized controlled trial, 122 patients (mean age 61.9 ± 10.5 years; left atrial diameter 43 ± 6 mm) with persistent AF (PeAF) or sustained (12 hours) paroxysmal AF (SusPAF) with risk factors for atrial substrate were included and followed up for 12 months. Patients were randomized to PVI-only or PVI + lines (left atrial roof line, mitral isthmus line, and tricuspid isthmus line) group. Holter monitoring was performed at 3, 6, and 12 months and according to symptoms. The primary outcome was atrial tachyarrhythmia recurrence lasting ≥30 seconds.Baseline characteristics were comparable between groups; 61% had PeAF and 39% SusPAF. Successful PVI was achieved for 98% of pulmonary veins, and bidirectional block was obtained in 90% of lines. The primary end point occurred in 38% of the PVI + lines group and 32% of the PVI-only group (P = .50), which was consistent in both PeAF (36% vs 28%; P = .45) and SusPAF (42% vs 39%; P = .86). Compared with the PVI-only group, the PVI + lines group had higher procedure duration (209 ± 52 minutes vs 172 ± 44 minutes; P.001), ablation time (4352 ± 1084 seconds vs 2503 ± 1061 seconds; P.001), and radiation exposure (Dose-area product 3992 ± 6496 Gy·cm(2) vs 2106 ± 1679 Gy·cm(2); P = .03). Quality of life (disease-specific Atrial Fibrillation Effect on Quality of Life questionnaire and mental component scale of the Short Form 36 Health Survey) improved significantly during the study but did not differ between groups.Adding lines to wide antral PVI in substrate-based AF requires significantly more ablation, increases procedure duration and radiation dose, but provides no additional clinical benefit.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, affecting 1.5–2% of the general population and more than 8% of those older than 80 years. Because of the progressive ageing of our population, an exponential increase in incidence is expected over the next few decades. Patients with AF have an increased mortality and morbidity, particularly owing to fatal or disabling stroke. The risk of embolic stroke is five times higher in the presence of AF, with an average annual rate around 5%, but there is a progressive increase with age and the presence of other risk factors, such as prior stroke or transient ischaemic attack, hypertension, diabetes mellitus, congestive heart failure, female sex, and vascular disease, as predicted by the CHADS2 and the CHA2DS2-VASc scores. Moreover, strokes associated with AF are more severe, with a 50% greater likelihood of becoming disabled or handicapped and more than 50% likelihood of death. Intracardiac thrombus formation due to the Virchow triad of events (endothelial or endocardial damage or dysfunction, abnormal blood stasis, and altered haemostasis, platelet function, and fibrinolysis) followed by distal embolization leads to thromboembolic events manifest as transient ischaemic attack, ischaemic stroke, and peripheral embolism in patients with AF.

BACKGROUND: To investigate the long term outcomes after catheter ablation (CA) of ventricular tachycardia (VT) in the context of structural heart disease in a multicenter cohort. The impact of different ablation strategies (substrate ablation versus activation guided versus combined) and non-inducibility as an end-point was evaluated. METHODS: Data was pooled from prospective registries at 5 centres over a 5 year period. Success was defined as survival free from recurrent ventricular arrhythmias (VA). Multivariate analysis of factors predicting survival free from VA was analysed by Cox regression. RESULTS: Five hundred sixty-six patients underwent CA for VT. Patients were 64 ± 15 years. Left ventricular ejection fraction was 35 ± 15% and 66% had ischaemic heart disease. At 2.3 (IQR 1.0-4.2) years, success was achieved in 44% after a single procedure, rising to 60% after repeat procedures. Mortality at final follow up was 22%. Multivariate analysis showed that higher left ventricular ejection fraction, younger age, ischaemic heart disease, and non-inducibility of VA predicted long term survival free from VA (all p

Objectives This study sought to assess the clinical efficacy, safety, and clinical utility of a novel electroanatomical mapping system. Background A new mapping system capable of rapidly acquiring detailed maps based on automatic annotation of thousands of points was recently released for clinical use. This is the first description of its utility in humans. Methods The first consecutive 20 cases (7 atrial tachycardia, 8 atrial fibrillation, 3 ventricular tachycardia, and 2 ventricular ectopic beat ablations) were analyzed. The system uses a bidirectional deflectable basket catheter with 64 closely spaced mini-electrodes. It automatically accepts and annotates electrograms when a number of predefined criteria are met. Results Thirty right atrial maps were acquired in 11 (4 to 15) min, consisting of 7,220 (3,467 to 10,947) points, 22 left atrial maps in 11 (6 to 19) min, consisting of 7,818 (4,379 to 12,262) points and 10 left ventricular maps in 37 (14 to 43) min, consisting of 8,709 (2,605 to 15,514) points. The mini-basket catheter could reach all areas of interest without deflectable sheaths. No embolic events, bleeding complications, or endocardial structure damage were observed. Correction of the automatic annotation was performed in 0.02% of points in 4 of 62 maps. The system revealed re-entry circuits of atrial tachyarrhythmias, identified gaps on linear lesions, and identified and correctly annotated the clinical ventricular ectopic beats and channels of slow conduction within ventricular scar. Conclusions The novel automatic mapping system was rapid, safe, and efficacious in mapping a variety of cardiac arrhythmias in humans. Further clinical research is needed to optimize its use in the ablation of complex arrhythmias.

Contact Force Sensing AF Ablation Outcomes Introduction Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown. Methods and Results First time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months—paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)—nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29–3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41–1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0–10.5] minutes; P < 0.001). Complication rates were similar in both groups. Conclusions At medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.

BACKGROUND: Tissue thickness at the site of ablation is a determinant of lesion transmurality. We reported the feasibility, safety and efficacy of long-standing persistent atrial fibrillation (PsAF) ablation, incorporating deliberate LAA isolation and occlusion and identified systematic differences in ostial LAA tissue thickness in a matched cohort of cadaveric specimens. METHODS: Pre-procedural CCT scans were acquired from 22 patients undergoing LAA isolation and subsequent occlusion. Using a novel CCT wall thickness algorithm, LAA ostial wall thickness was assessed in vivo, compared with measurements from the cadaveric specimens and analysed for differences between regions that demonstrated acute electrical reconnection and those that did not. RESULTS: Mean tissue thickness calculated for each LAA ostial quadrant was 2.1(+/-0.6)mm (anterior quadrant), 1.9(+/-0.4)mm (superior quadrant), 1.5(+/-0.4)mm (posterior quadrant) and 1.8(+/-0.7)mm (inferior quadrant). Tissue was significantly thicker in the anterior (p = 0.004) and superior quadrants (p = 0.014) than the posterior quadrant. Higher thickness measurements were recorded from quadrants demonstrated to be thicker from histology. Tissue was significantly thicker in regions that demonstrated acute electrical reconnection (1.9(+/-0.6)mm) when compared with those that did not (1.6(+/-0.5)mm) (p = 0.008). CONCLUSIONS: CCT imaging may be used to detect differences in wall thickness at different atrial locations and success of LAA ablation may be affected by local tissue thickness. Atrial wall thickness may need to be considered as a metric to guide titration of radiofrequency (RF) energy for safe and successful ablation. This article is protected by copyright. All rights reserved.

Background— Catheter ablation (CA) is commonly performed for persistent atrial fibrillation, but few high-quality randomized controlled trials (RCTs) exist, leading to funding restrictions being proposed in several countries. We performed a random-effects meta-analysis of RCTs and non-RCTs to assess the efficacy of CA for persistent atrial fibrillation. Methods and Results— We systematically searched PubMed, EMBASE, CENTRAL, OpenGrey, and clinicaltrials.gov for RCTs and non-RCTs reporting clinical outcomes after CA for persistent atrial fibrillation. Forty-six eligible studies were identified containing 3819 patients. After a single procedure, CA significantly reduced the risk of recurrent atrial fibrillation compared with medical therapy (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.20–0.53; P P =0.01), and electrical isolation reduced AF recurrence compared with purely anatomic encirclement (OR, 0.33; 95% CI, 0.13–0.86; P =0.02). Linear ablation within the left atrium (OR, 0.22; 95% CI, 0.10–0.49; P P =0.15), significantly reduced AF recurrence. Results were not improved by performing more extensive linear lesion sets (OR, 0.77; 95% CI, 0.41–1.43; P =0.40) or from biatrial ablation (OR, 0.62; 95% CI, 0.31–1.24; P =0.17). Where data were available, the relative benefits seen held true both after a single or multiple procedure(s). Sensitivity analyses showed that inclusion of non-RCTs increased statistical power without biasing the calculated effect sizes. Conclusions— For patients with persistent atrial fibrillation, CA achieves significantly greater freedom from recurrent atrial fibrillation compared with medical therapy. The most efficacious strategy is likely to combine isolation of the pulmonary veins with limited linear ablation within the left atrium.

Background The mapping of ventricular arrhythmias in humans using a minibasket 64-electrode catheter paired with a novel automatic mapping system (Rhythmia) has not been evaluated. Objective The purpose of this study was to evaluate the safety and efficacy of mapping ventricular arrhythmias and clinical outcomes after ablation using this system. Methods Electroanatomic maps for ventricular arrhythmias were obtained during 20 consecutive procedures in 19 patients (12 with ventricular tachycardia [VT] and 2 with ventricular ectopy [VE]). High-density maps were acquired using automatic beat acceptance and automatic system annotation of electrograms. Results Forty-seven electroanatomic maps (including 3 right ventricular and 9 epicardial maps) were obtained. Left ventricular endocardial mapping by transseptal (n = 13) and/or transaortic (n = 11) access was safe with no complications related to the minibasket catheter. VT substrate maps (n = 14; median 10,184 points) consistently demonstrated late potentials with high resolution. VT activation maps (n = 25; median 6401 points) obtained by automatic annotation included 7 complete maps (covering ≥90% of the tachycardia cycle length) in 5 patients in whom the entire VT circuit was accurately visualized. VE timing maps (n = 8) successfully localized the origin of VEs in all, with all accepted beats consistent with clinical VEs. Over a median follow-up of 10 months, no arrhythmia recurrence was noted in 75% after VT ablation and 86% after VE ablation. Conclusion In this first human experience for ventricular arrhythmias using this system, ultra-high-density maps were created rapidly and safely, with a reliable automatic annotation of VT and consistent recording of abnormal electrograms. Medium-term outcomes after ablation were encouraging. Further larger studies are needed to validate these findings.

We thank Vroomen et al1 for their letter detailing the benefits of hybrid atrial fibrillation ablation, involving thoracoscopic epicardial ablation combined with endocardial catheter ablation followed by an epicardial left atrial appendage (LAA) clip procedure, performed in an experienced center.2 However, wider adoption of this approach as routine clinical practice is not without concerns. Epicardial LAA closure/excision has been performed for many years although follow-up imaging studies have shown that successful closure using a variety of closure techniques may only range between 0% and 73%. Importantly, a significant proportion of patients with unsuccessful closure had evidence …

This study aimed at assessing the feasibility and long-term efficacy of left atrial appendage occlusion (LAAO) in a "real world" setting.Although LAAO has recently emerged as an alternative to oral anticoagulants in patients with atrial fibrillation for the prevention of thromboembolic stroke, "real world" data about the procedure with different devices are lacking.Eight centers in the United Kingdom contributed to a retrospective registry for LAAO procedures undertaken between July 2009 and November 2014.A total of 371 patients (72.9 ± 8.3 years old, 88.9% males) were enrolled. The overall procedure success was 92.5%, with major events in 3.5% of cases. The device choice was Watchman in 63% of cases, Amplatzer Cardiac Plug in 34.7%, Lariat in 1.7%, and Coherex WaveCrest in 0.6%. A significant improvement in procedure success (from 89.2% to 95.7%; P = 0.018) and reduction of acute major complications (from 6.5% to 0.5%; P = 0.001) were observed between procedures in the first and the second half of the recruitment time. An annual 90.1% relative risk reduction (RRR) for ischemic stroke, an 87.2% thromboembolic events RRR, and a 92.9% major bleeding RRR were observed, if compared with the predicted annual risks based on CHADS2, CHA2DS2-Vasc, and HAS-BLED scores, respectively, over a follow-up period of 24.7 ± 16.07 months.LAAO can be performed safely in a real world setting with good implant success rates and procedural outcomes. The long-term benefits of the procedure are reassuring in terms of both ischemic events and avoidance of severe bleeding associated with anticoagulation in this patient group. © 2016 Wiley Periodicals, Inc.

Background— Left atrial appendage (LAA) electric isolation is reported to improve persistent atrial fibrillation (AF) ablation outcomes. However, loss of LAA mechanical function may increase thromboembolic risk. Concomitant LAA electric isolation and occlusion as part of conventional AF ablation has never been tested in humans. We therefore evaluated the feasibility, safety, and efficacy of LAA electric isolation and occlusion in patients undergoing long-standing persistent AF ablation. Methods and Results— Patients with long-standing persistent AF (age, 68±7 years; left atrium diameter, 46±3 mm; and AF duration, 25±15 months) underwent AF ablation, LAA electric isolation, and occlusion. Outcomes were compared with a balanced (1:2 ratio) control group who had AF ablation alone. Among 22 patients who underwent ablation, LAA electric isolation was possible in 20. Intraprocedural LAA reconnection occurred in 17 of 20 (85%) patients, predominantly at anterior and superior locations. All were reisolated. LAA occlusion was successful in all 20 patients. There were no major periprocedural complications. Imaging at 45 days and 9 months confirmed satisfactory device position and excluded pericardial effusion. One of twenty (5%) patients had a gap of ≥5 mm requiring anticoagulation. Nineteen of twenty (95%) patients stopped warfarin at 3 months. Without antiarrhythmic drugs, freedom from AF at 12 months after a single procedure was significantly higher in the study group (19/20, 95%) than in the control group (25/40, 63%), P =0.036. Freedom from atrial arrhythmias was demonstrated in 12 of 20 (60%) and 18 of 20 (90%) patients after 1 and ≤2 procedures (mean, 1.3), respectively. Conclusions— Persistent AF ablation, LAA electric isolation, and mechanical occlusion can be performed concomitantly. This technique may improve the success of persistent AF ablation while obviating the need for chronic anticoagulation. Clinical Trial Registration— URL: https://clinicaltrials.gov . Unique identifier: NCT02028130.

This study sought to assess the clinical efficacy, safety, and clinical utility of a novel electroanatomical mapping system.A new mapping system capable of rapidly acquiring detailed maps based on automatic annotation of thousands of points was recently released for clinical use. This is the first description of its utility in humans.The first consecutive 20 cases (7 atrial tachycardia, 8 atrial fibrillation, 3 ventricular tachycardia, and 2 ventricular ectopic beat ablations) were analyzed. The system uses a bidirectional deflectable basket catheter with 64 closely spaced mini-electrodes. It automatically accepts and annotates electrograms when a number of predefined criteria are met.Thirty right atrial maps were acquired in 11 (4 to 15) min, consisting of 7,220 (3,467 to 10,947) points, 22 left atrial maps in 11 (6 to 19) min, consisting of 7,818 (4,379 to 12,262) points and 10 left ventricular maps in 37 (14 to 43) min, consisting of 8,709 (2,605 to 15,514) points. The mini-basket catheter could reach all areas of interest without deflectable sheaths. No embolic events, bleeding complications, or endocardial structure damage were observed. Correction of the automatic annotation was performed in 0.02% of points in 4 of 62 maps. The system revealed re-entry circuits of atrial tachyarrhythmias, identified gaps on linear lesions, and identified and correctly annotated the clinical ventricular ectopic beats and channels of slow conduction within ventricular scar.The novel automatic mapping system was rapid, safe, and efficacious in mapping a variety of cardiac arrhythmias in humans. Further clinical research is needed to optimize its use in the ablation of complex arrhythmias.

Contact force sensing (CFS) technology improves acute pulmonary vein isolation durability; however, its impact on the clinical outcome of ablating atrial fibrillation (AF) is unknown.First time AF ablation procedures employing CFS from 4 centers were matched retrospectively to those without CFS in a 1:2 manner by type of AF. Freedom from atrial tachyarrhythmia was defined as the primary outcome measure, and fluoroscopy time the secondary outcome measure. Nineteen possible explanatory variables were tested in addition to CFS. A total of 600 AF ablation procedures (200 using CFS and 400 using non-CFS catheters) performed between 2010 and 2012 (46% paroxysmal, 36% persistent, 18% long-lasting persistent) were analyzed. The mean follow-up duration was 11.4 ± 4.7 months-paroxysmal AF 11.2 ± 4.1 CFS versus 11.3 ± 3.9 non-CFS (P = 0.745)-nonparoxysmal AF 10.4 ± 4.5 CFS versus 11.9 ± 5.4 non-CFS (P = 0.015). The use of a CFS catheter independently predicted clinical success in ablating paroxysmal AF (HR 2.24 [95% CIs 1.29-3.90]; P = 0.004), but not nonparoxysmal AF (HR 0.73 [0.41-1.30]; P = 0.289) in a multivariate analysis that included follow-up duration. Among all cases, the use of CFS catheters was associated with reduced fluoroscopy time in multivariate analysis (reduction by 7.7 [5.0-10.5] minutes; P0.001). Complication rates were similar in both groups.At medium-term follow-up, CFS catheter technology is associated with significantly improved outcome of first time catheter ablation of paroxysmal AF, but not nonparoxysmal AF. Fluoroscopy time was lower when CFS technology was employed in all types of AF ablation procedures.

Background Left atrial appendage (LAA) electrical isolation is reported to improve atrial fibrillation ablation outcomes. However, loss of mechanical function may increase thromboembolic risk. Objective The aim of this study was to evaluate the feasibility and safety of LAA occlusion after electrical isolation in a canine model. Methods Nine canines underwent LAA isolation with irrigated radiofrequency ablation after pulmonary vein (PV) isolation. Entrance and exit block were confirmed with intravenous adenosine after 30 minutes. The LAA was then occluded with a Watchman device. Device position was assessed at 10 days by using transthoracic echocardiography. At 45 days, LAA isolation was assessed epicardially. Hearts were then examined macroscopically and histologically. Results All 36 PVs and 8 of 9 LAAs (89%) were electrically isolated. Acute LAA reconnection occurred in 4 of 8 LAAs (50%). All were reisolated. The mean ablation time was 51 ± 19 minutes, including 24 ± 18 minutes for LAA isolation. LAA occlusion was successful in all cases. One animal died of a primary intracranial bleed due to anticoagulant hypersensitivity 36 hours after the procedure. Transthoracic echocardiography at 10 days confirmed satisfactory device positions and no pericardial effusion. At 45 days, 7 of 8 (88%) had persistent LAA electrical isolation. All devices were stable without evidence of erosion. Microscopy revealed complete device-tissue apposition and a mature connective tissue layer overlying the device surface in all cases. Conclusion LAA electrical isolation and mechanical occlusion can be performed concomitantly in this animal model, with no displacement or mechanical erosion of the appendage at 45 days. This technique can potentially improve success rates and obviate the need for chronic anticoagulation. Future studies should address efficacy, safety, and feasibility in humans.

Cardioembolic stroke is an important complication of atrial fibrillation. The thrombus responsible for this arises from the left atrial appendage (LAA) in >90% of cases, providing the rationale for device-based LAA closure as a means of thromboprophylaxis. Although oral anticoagulant therapy remains the mainstay for reducing the risk of stroke in patients with atrial fibrillation, an increasing number of patients, particularly those ineligible for conventional pharmacotherapy, are being offered percutaneous left atrial appendage closure. Cardiovascular CT can provide important information to assess the suitability of patients for LAA interventions and guide device selection and approach. The high spatial resolution and multiplanar capability of contemporary contrast-enhanced gated multidetector cardiovascular CT render it an ideal modality for noninvasively evaluating patients before intervention and assessing patients after intervention both for complications and procedural outcome.

Background Contact force (CF) sensing technology allows real time CF measurement during catheter ablation. We hypothesised that the use of CF technology during pulmonary vein isolation (PVI) for atrial fibrillation (AF) would translate into lower acute pulmonary vein (PV) reconnection rates. Methods and results Symptomatic AF patients were treated in two groups, ‘unblinded' and ‘blinded', each containing 20 patients undergoing first time PVI. An irrigated radiofrequency CF sensing catheter was used in both groups. In the ‘unblinded' group, the operator could view the CF value during mapping and ablation in real time. In the ‘blinded group', the operator was ‘blinded' to this information during the procedure, although the data were recorded. All 80 PVs were successfully isolated with exit and entrance block re-tested after 1h with adenosine. There was a significant association between blinding and the rate of acute PV reconnection. 17/80 (21%) of the PVs in the blinded subjects had a reconnection while 3/80 (4%) of the PVs in the unblinded subjects had a reconnection (p=0.001). Blinding the operator resulted in lower mean CF overall (11.6g (10.5, 12.9g) vs. 14.4g (13.3, 15.7g); p=0.002). Sites where applied CF was significantly lower than others were usually the sites where reconnection occurred: these were the ridge between the left upper PV and appendage, and the right carina. Conclusions CF data identified key areas where CF was poor. These were the areas of acute reconnection. Availability of real time CF information during PVI was associated with a significantly lower acute pulmonary vein reconnection rate.

Introduction: Recent evidence supports left atrial appendage closure (LAAC) as a cost-effective alternative to warfarin. However these findings, based on clinical trial populations, may not be generalisable to clinical practice. The cost-impact of a real world experience of LAAC compared with warfar