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Background: Long-term clinical outcomes of catheter ablation (CA) compared to thoracoscopic surgical ablation (SA) to treat patients with long-standing persistent atrial fibrillation (LSPAF) are not known., Objective: The purpose of this study was to compare the long-term (36-month) clinical efficacy, quality of life, and cost-effectiveness of SA and CA in LSPAF., Methods: Participants were followed up for 3 years using implantable loop recorders and questionnaires to assess the change in quality of life. Intention-to-treat analyses were used to report the findings., Results: Of the 115 patients with LSPAF treated, 104 (90.4%) completed 36-month follow-up [CA: n = 57 (95%); SA: n = 47 (85%)]. After a single procedure without antiarrhythmic drugs, 7 patients (12%) in the CA arm and 5 (11%) in the SA arm [hazard ratio 1.22; 95% confidence interval (CI) 0.81-1.83; P = .41] were free from atrial fibrillation/tachycardia (AF/AT) ≥30 seconds at 36 months. Thirty-three patients (58%) in the CA arm and 26 (55%) in the SA arm (hazard ratio 1.04; 95% CI 0.57-1.88; P = .91) had their AF/AT burden reduced by ≥75%. The overall impact on health-related quality of life was similar, with mean quality-adjusted life year estimates of 2.45 (95% CI 2.31-2.59) for CA and 2.32 (95% CI 2.13-2.52) for SA. Estimated costs were higher for SA (mean £24,682; 95% CI £21,746-£27,618) than for CA (mean £18,002; 95% CI £15,422-£20,581)., Conclusion: In symptomatic LSPAF, CA and SA were equally effective at achieving arrhythmia outcomes (freedom from AF/AT ≥30 seconds and ≥75% burden reduction) after a single procedure without antiarrhythmic drugs. However, SA is significantly more costly than CA., Competing Interests: Disclosures The authors have no conflicts of interest to disclose., (Crown Copyright © 2024. Published by Elsevier Inc. All rights reserved.)

Background: In nonvalvular atrial fibrillation (NVAF), the left atrial appendage (LAA) is the source of thrombus in up to 90% of patients. LAA pseudothrombus (LAAPT), defined as a filling defect on the initial but not the 60-second delayed acquisition on cardiovascular computed tomography scan (CCT), is a recognized phenomenon in NVAF, with unknown clinical relevance. We aimed to determine the relationship between LAAPT and history of stroke in patients with NVAF., Methods and Results: The study included 213 consecutive patients with NVAF undergoing CCT who were assessed for LAAPT. LA and LAA dimensions and LAA morphology correlated with clinical demographics including cardiovascular risk factors, history of stroke, thromboembolic stroke, and transient ischemic attack. Mean age (±SD) was 65.1±10.5 years (range 31-89) and 150 of 213 (70.4%) were men. LAAPT was present in 59 of 213 (27.7%) patients. Greater mean LAA ostium area (5.7 versus 4.5, P <0.001), greater mean LAA ostium area:curved length (0.11 versus 0.08, P <0.001), increased LAA volume (14.0 versus 10.2, P <0.001), and lower mean LAA tortuosity index (1.17 versus 1.38, P <0.001) were all associated with the presence of LAAPT. On multivariable analysis, LAAPT on CCT (odds ratio [OR], 3.20 [95% CI, 1.40-7.20]; P <0.006) and higher CHA 2 DS 2 -VASc score (OR, 1.65 [95% CI, 1.16-2.35]; P =0.01) were associated with all strokes, with LAAPT remaining a statistically significant risk factor even after adjustment for CHA 2 DS 2 -VASc score., Conclusions: LAAPT on CCT is common in patients with NVAF. It has a strong positive association with stroke prevalence, even after adjustment for CHA 2 DS 2 -VASc score. LAAPT on CCT may potentially allow further stratification for stroke risk, additive to the CHA 2 DS 2 -VASc score.

Aims: This proof-of-concept study sought to evaluate changes in heart rate (HR) obtained from a consumer wearable device and compare against implantable loop recorder (ILR)-detected recurrence of atrial fibrillation (AF) and atrial tachycardia (AT) after AF ablation., Methods and Results: REMOTE-AF (NCT05037136) was a prospectively designed sub-study of the CASA-AF randomized controlled trial (NCT04280042). Participants without a permanent pacemaker had an ILR implanted at their index ablation procedure for longstanding persistent AF. Heart rate and step count were continuously monitored using photoplethysmography (PPG) from a commercially available wrist-worn wearable. Photoplethysmography-recorded HR data were pre-processed with noise filtration and episodes at 1-min interval over 30 min of HR elevations ( Z -score = 2) were compared with corresponding ILR data. Thirty-five patients were enrolled, with mean age 70.3 ± 6.8 years and median follow-up 10 months (interquartile range 8-12 months). Implantable loop recorder analysis revealed 17 out of 35 patients (49%) had recurrence of AF/AT. Compared with ILR recurrence, wearable-derived elevations in HR ≥ 110 beats per minute had a sensitivity of 95.3%, specificity 54.1%, positive predictive value (PPV) 15.8%, negative predictive value (NPV) 99.2%, and overall accuracy 57.4%. With PPG-recorded HR elevation spikes (non-exercise related), the sensitivity was 87.5%, specificity 62.2%, PPV 39.2%, NPV 92.3%, and overall accuracy 64.0% in the entire patient cohort. In the AF/AT recurrence only group, sensitivity was 87.6%, specificity 68.3%, PPV 53.6%, NPV 93.0%, and overall accuracy 75.0%., Conclusion: Consumer wearable devices have the potential to contribute to arrhythmia detection after AF ablation., Study Registration: ClinicalTrials.gov Identifier: NCT05037136 https://clinicaltrials.gov/ct2/show/NCT05037136., Competing Interests: Conflict of interest: S.G. reports funding through the BigData@Heart Innovative Medicines Initiative [grant no. 116074]. A.B. reports funding from the BigData@Heart Innovative Medicines Initiative [grant no. 116074] during the conduct of the study. D.K. reports grants from the National Institute for Health Research (NIHR CDF-2015-08-074 RATE-AF; NIHR130280 DaRe2THINK; NIHR132974 D2T-NeuroVascular; and NIHR203326 BRC), the British Heart Foundation (PG/17/55/33087, AA/18/2/34218, and FS/CDRF/21/21032), the EU/EFPIA Innovative Medicines Initiative (BigData@Heart 116074), EU Horizon (HYPERMARKER 101095480), UK National Health Service—Data for R&D—Subnational Secure Data Environment programme, and the ESC supported by educational grants from Boehringer Ingelheim/BMS-Pfizer Alliance/Bayer/Daiichi Sankyo/Boston Scientific, the NIHR/University of Oxford Biomedical Research Centre, and British Heart Foundation/University of Birmingham Accelerator Award (STEEER-AF). In addition, he has received research grants and advisory board fees from Bayer, Amomed, and Protherics Medicines Development; all outside the submitted work. G.G. reports support from the NIHR Birmingham Experimental Cancer Medicine Centre, NIHR Birmingham Surgical Reconstruction and Microbiology Research Centre, Nanocommons H2020-EU (731032), and the MRC Heath Data Research UK (HDRUK/CFC/01). S.H. reports speaker fees from Alivercor, consultancy fees from BMS, a research grant from Abbott, and the NIHR grants (CASA and LOTO). G.A., I.K.H., Z.C., J.J., D.J., V.M., W.H., and T.W. have no relevant disclosures., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Leadless pacemakers (LPs) may mitigate the risk of lead failure and pocket infection related to conventional transvenous pacemakers. Atrial LPs are currently being investigated. However, the optimal and safest implant site is not known., Objectives: We aimed to evaluate the right atrial (RA) anatomy and the adjacent structures using complementary analytic models [gross anatomy, cardiac magnetic resonance imaging (MRI), and computer simulation], to identify the optimal safest location to implant an atrial LP human., Methods and Results: Wall thickness and anatomic relationships of the RA were studied in 45 formalin-preserved human hearts. In vivo RA anatomy was assessed in 100 cardiac MRI scans. Finally, 3D collision modelling was undertaken assessing for mechanical device interaction. Three potential locations for an atrial LP were identified; the right atrial appendage (RAA) base, apex, and RA lateral wall. The RAA base had a wall thickness of 2.7 ± 1.6 mm, with a low incidence of collision in virtual implants. The anteromedial recess of the RAA apex had a wall thickness of only 1.3 ± 0.4 mm and minimal interaction in the collision modelling. The RA lateral wall thickness was 2.6 ± 0.9 mm but is in close proximity to the phrenic nerve and sinoatrial artery., Conclusions: Based on anatomical review and 3D modelling, the best compromise for an atrial LP implantation may be the RAA base (low incidence of collision, relatively thick myocardial tissue, and without proximity to relevant epicardial structures); the anteromedial recess of the RAA apex and lateral wall are alternate sites. The mid-RAA, RA/superior vena cava junction, and septum appear to be sub-optimal fixation locations., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Introduction: It is not known whether the optimal atrioventricular (AV opt ) delay varies between left ventricular (LV) pacing site during endocardial biventricular pacing (BiVP) and may therefore needs consideration., Methods: We assessed the hemodynamic AV opt in patients with chronic heart failure undergoing endocardial LV lead implantation. AV opt was assessed during atrio-BiVP with a "roving LV lead." Up to four locations were studied: mid-lateral wall, mid-septum (or a close alternative), site of greatest hemodynamic improvement, and LV lead implant site. The AV opt was compared to a fixed AV delay of 180 ms., Results: Seventeen patients were included (12 male, aged 66.5 ± 12.8 years, ejection fraction 26 ± 7%, 16 left bundle branch block or high percentage of right ventricular pacing [RVP], QRS duration 167 ± 27 ms). In most locations (62/63), AV opt increased systolic blood pressure during BiVP compared with RVP (relative improvement 6 mmHg, interquartile range [IQR] 4-9 mmHg). Compared to a fixed AV delay, the hemodynamic improvement at AV opt was higher (1 mmHg, IQR 0.2-2.6 mmHg, p < .001). Within most patients (16/17), we observed a difference in AV opt between pacing sites (median paced AV opt 209 ms, IQR 117-250). Within this range, the hemodynamic impact of these differences was small (median loss 0.6 mmHg, IQR 0.1-2.6 mmHg)., Conclusion: Within a patient, different endocardial LV lead locations have slightly different hemodynamic AV opt which are superior to a fixed AV delay. The hemodynamic consequence of applying an optimum from a different lead location is small., (© 2023 The Authors. Journal of Cardiovascular Electrophysiology published by Wiley Periodicals LLC.)

Background: Left atrial (LA) function following catheter or surgical ablation of de-novo long-standing persistent atrial fibrillation (AF) and its impact on AF recurrence was studied in patients participating in the CASA-AF trial (Catheter Ablation vs. Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation)., Methods: All patients underwent echocardiography preablation, 3 and 12 months post-ablation. LA structure and function were assessed by 2-dimensional volume and speckle tracking strain measurements of LA reservoir, conduit, and contractile strain. Left ventricular diastolic function was measured using transmitral Doppler filling velocities and myocardial tissue Doppler velocities to derive the e', E/e', and E/A ratios. Continuous rhythm monitoring was achieved using an implantable loop recorder., Results: Eighty-three patients had echocardiographic data suitable for analysis. Their mean age was 63.6±9.7 years, 73.5% were male, had AF for 22.8±11.6 months, and had a mean LA maximum volume of 48.8±13.8 mL/m 2 . Thirty patients maintained sinus rhythm, and 53 developed AF recurrence. Ablation led to similar reductions in LA volumes at follow-up in both rhythm groups. However, higher LA emptying fraction (36.3±10.6% versus 27.9±9.9%; P <0.001), reservoir strain (22.6±8.5% versus 16.7±5.7%; P =0.001), and contractile strain (9.2±3.4% versus 5.6±2.5%; P <0.001) were noted in the sinus rhythm compared with AF recurrence group following ablation at 3 months. Diastolic function was better in the sinus rhythm compared with the AF recurrence group with an E/A ratio of 1.5±0.5 versus 2.2±1.2 ( P <0.001) and left ventricular E/e' ratio of 8.0±2.1 versus 10.3±4.1 ( P <0.001), respectively. LA contractile strain at 3 months was the only independent predictor of AF recurrence., Conclusions: Following ablation for long-standing persistent AF, improvement in LA function was greater in those who maintained sinus rhythm. LA contractile strain at 3 months was the most important determinant of AF recurrence following ablation., Registration: URL: https://www., Clinicaltrials: gov; Unique identifier: NCT02755688., Competing Interests: Disclosures Dr Khan received presentation fees from CHRS and NIHR grant (EME 12/127/127); Dr Haldar received a grant from NIHR (EME 12/127/127), Abbott, presentation fees from Alivecor and Zurich Heart House; Dr Bahrami received honoraria fees from Medtronic and meeting support from Edwards Lifesciences; Dr De Souza received presentation/support fees from Medtronic and Atricure. Dr De Souza is serving as BISICS President; Dr Markides received educational grants, consultancy fees, and honoraria from Biosense Webster; Dr Jones receives institutional research grants from Biosense Webster, Boston Scientific, and Medtronic; the rest of the authors disclose no conflicts of interest.

Aims: Left bundle branch area pacing (LBBAP) has been shown to be effective and safe. Limited data are available on LBBAP in the congenital heart disease (CHD) population. This study aims to describe the feasibility and safety of LBBAP in CHD patients compared with non-CHD patients., Methods and Results: This is a single-centre, non-randomized observational study recruiting consecutive patients with bradycardia indication. Demographic data, ECGs, imaging, and procedural data including lead parameters were recorded. A total of 39 patients were included: CHD group (n = 13) and non-CHD group (n = 26). Congenital heart disease patients were younger (55 ± 14.5 years vs. 73.2 ± 13.1, P < 0.001). Acute success was achieved in all CHD patients and 96% (25/26) of non-CHD patients. No complications were encountered in either group. The procedural time for CHD patients was comparable (96.4 ± 54 vs. 82.1 ± 37.9 min, P = 0.356). Sheath reshaping was required in 7 of 13 CHD patients but only in 1 of 26 non-CHD patients, reflecting the complex and distorted anatomy of the patients in this group. Lead parameters were similar in both groups; R wave (11 ± 7 mV vs. 11.5 ± 7.5, P = 0.881) and pacing threshold (0.6 ± 0.3 V vs. 0.7 ± 0.3, P = 0.392). Baseline QRS duration was longer in the CHD group (150 ± 28.2 vs. 118.6 ± 26.6 ms, P = 0.002). Despite a numerically greater reduction in QRS and a similar left ventricular activation time (65.9 ± 6.2 vs. 67 ± 16.8 ms, P = 0.840), the QRS remained longer in the CHD group (135.5 ± 22.4 vs. 106.9 ± 24.7 ms, P = 0.005)., Conclusion: Left bundle branch area pacing is feasible and safe in CHD patients as compared to that in non-CHD patients. Procedural and fluoroscopy times did not differ between both groups. Lead parameters were satisfactory and stable over a short-term follow-up., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Introduction: Conduction system pacing (CSP), consisting of His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) is a rapidly developing field. These pacing techniques result in single lead left ventricular resynchronisation. Understanding of the associated learning curve of the two techniques is an important consideration for new implanters/implanting centres., Methods: We conducted a review of the first 30 cases of both HBP and LBBAP at The Royal Brompton Hospital. The procedural duration and fluoroscopy time were used as surrogates for the learning curve of each technique., Results: Patient characteristics were similar in HBP and LBBAP groups; LV ejection fraction (46% vs 54%, p = 0.08), pre-procedural QRS duration (119 ms vs 128 ms, p = 0.32).Mean procedural duration was shorter for LBBAP than for HBP (87 vs 107mins, p = 0.04) and the drop in procedural duration was more marked in LBBAP, plateauing and remaining low at 80mins after the initial 10 cases. Fluoroscopic screening time mirrored procedural duration (8 min vs 16 min, p < 0.01)., Discussion/conclusion: Our data suggest that the CSP learning curve was shorter for LBBAP than for HBP and appears to plateaux after the first 10 cases, however the HBP learning curve is longer with continued improvement over the first 30 cases. The shorter learning curve of LBBAP in conjunction with the superior electrical parameters and simplified programming mean the establishment of a CSP program is potentially easier with LBBAP compared to with HBP., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 Published by Elsevier B.V.)

Aims: The ARC-HF and CAMTAF trials randomized patients with persistent atrial fibrillation (AF) and heart failure (HF) to early routine catheter ablation (ER-CA) versus pharmacological rate control (RC). After trial completion, delayed selective catheter ablation (DS-CA) was performed where clinically indicated in the RC group. We hypothesized that ER-CA would result in a lower risk of cardiovascular hospitalization and death versus DS-CA in this population., Methods and Results: Overall, 102 patients were randomized (age 60 ± 11 years, left ventricular ejection fraction [LVEF] 31 ± 11%): 52 to ER-CA and 50 to RC. After 12 months, patients undergoing ER-CA had improved self-reported symptom scores, lower New York Heart Association class (i.e. better functional capacity), and higher LVEF compared to patients receiving RC alone. During a median follow-up of 7.8 (interquartile range 3.9-9.9) years, 27 (54%) patients in the RC group underwent DS-CA and 34 (33.3%) patients died, including 17 (32.7%) randomized to ER-CA and 17 (34.0%) randomized to RC. Compared with DS-CA, a strategy of ER-CA exhibited similar risk of all-cause mortality (adjusted hazard ratio [aHR] 0.89, 95% confidence interval [CI] 0.44-1.77, p = 0.731) and combined all-cause mortality or cardiovascular hospitalization (aHR 0.80, 95% CI 0.43-1.47, p = 0.467). However, analyses according to treatment received suggested an association between CA and improved outcomes versus RC (all-cause mortality: aHR 0.43, 95% CI 0.20-0.91, p = 0.028; all-cause mortality/cardiovascular hospitalization: aHR 0.48, 95% CI 0.24-0.94, p = 0.031)., Conclusions: In patients with persistent AF and HF, ER-CA produces similar long-term outcomes to a DS-CA strategy. The association between CA as a treatment received and improved outcomes means there is still a lack of clarity regarding the role of early CA in selected patients. Randomized trials are needed to clarify this question., (© 2022 The Authors. European Journal of Heart Failure published by John Wiley & Sons Ltd on behalf of European Society of Cardiology.)

Purpose: We aimed to evaluate whether outcomes with ablation in persistent (PsAF) and long-standing persistent (LsPsAF) AF can be improved beyond what can be achieved with pulmonary vein isolation (PVI) alone, using individualized mapping to guide ablation., Methods: We studied 20 pts (15 M, 68 ± 11y) with PsAF (14) or LsPsAF (6) referred for first-time AF ablation. Following antral PVI, individualized mapping (IM) was performed using a high-density mapping catheter stably and fully deployed for 30 s at each of 23 ± 9 sites per patient. Activation data were reviewed, and an ablation strategy designed to intersect areas of focal and rotational activity. Mean follow-up was 429 ± 131 days. The study population was compared to a matched contemporary control cohort (CC) of 20 consecutive patients undergoing conventional ablation., Results: Despite the IM group having a higher median comorbidities score, 3.5 vs. 2.5 in the CC group, indicating potentially more complex patients and more advanced substrate, cumulative freedom from AF after a single procedure was achieved in 94% of patients in the IM group vs. 75% in the CC group at 1 year and remained the same in both groups at the conclusion of the study (p = 0.02). There was a similar trend in atrial arrhythmia-free survival between both groups (84% vs. 67% at 1 year) that did not reach statistical significance. The procedure duration was longer in the IM group by a median of 31.5 min (p = 0.004)., Conclusions: Individualized mapping to guide AF ablation appears to achieve significantly greater AF-free survival compared to conventional PVI when applied as a primary ablation treatment. The results of this pilot study need to be confirmed in a larger, randomized trial., (© 2022. The Author(s).)

Background: Patients with adult congenital heart disease (ACHD) are a rapidly growing cardiovascular population with increasing health needs and co-morbidities. Furthermore, their management requires frequent and ongoing hospital visits which can be burdensome. Digital health and remote monitoring have been shown to have a vast potential to enhance delivery of healthcare for patients, reducing their need for travel to clinic appointments therefore reducing costs to the patient and the healthcare service., Methods: Patients over the age of 16 with a diagnosis of ACHD were invited to use the tailored digital application too. They were monitored for a period of 6 months. Information on patient demographics, time using the application, flagged events that prompted clinical reviews and their feedback through patient surveys were collected., Results: A total of 103 patients were enrolled and registered to use the digital application tool. There were 57 (56%) males, median age at the time of enrolment was 39 (16-73) years. The majority (96%) had a moderate or complex ACHD according to the ACC/AHA classification. There was a total of 7 modules that were completed on a weekly basis. The median length of a participant session was 2.2 min and the mean time to complete a module was 21 s. In total, 35 (67%) felt that the application helped them better manage their cardiac condition. Almost all (94%) of patients expressed that they would like to continue using the application beyond the pilot. There were 18 flagged events during the 6 month observation period, and 50% of received early clinical intervention., Conclusion: Application based remote monitoring in this select group was well received and potentially holds large benefit to patients both clinically and economically. There were no safety concerns in our pilot feasibility study. Our data may inform much needed and timely investment in digital health., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Purpose: We aimed to assess the feasibility, safety, and operator feedback of a novel star-shaped high-density mapping catheter containing 48 platinum-iridium mapping electrodes distributed across eight spines., Methods: This prospective, single-arm, first-in-human study was conducted at five European sites. Primary endpoints were completion of pre-ablation mapping requirements, obtaining clinically indicated mapping with the new catheter without resorting to non-study mapping catheters, and incidence of serious adverse events (SAEs). Physician feedback survey assessed catheter performance, including deployment, ease of use, and mapping results. The subjects were followed for 7 days post-procedure., Results: Of 31 patients enrolled (11 ventricular tachycardia [VT], 10 scar-related atrial tachycardia [AT]/atypical atrial flutter [AFL], and 10 persistent atrial fibrillation [PsAF]), 28 had study catheter inserted for mapping purposes. Pre-ablation mapping was achieved in 23/28 patients (82.1%). Median of total pre-ablation mapping times were 121.0, 72.5, and 31.5 min for the VT, scar-related AT/atypical AFL, and PsAF subgroups, respectively. More than two-thirds of mapping points acquired were used to generate CARTO maps relevant for ablation. All 16 patients who had conduction channel(s), gaps(s), or critical isthmus identified had the areas successfully mapped. The ability to deploy, maneuver, and reach the atria and ventricles using the catheter was rated positively for most procedures. Only one SAE (heart failure) was reported, unrelated to the device., Conclusion: The study results demonstrate the feasibility of the OCTARAY catheter to successfully map complex arrhythmias with good safety profile. Operator feedback indicates satisfaction with ease of use and maneuverability of the catheter., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: Conventional superior access for cardiac implantable electronic devices (CIEDs) is not always possible and femoral CIEDs (F-CIED) are an alternative option when leadless systems are not suitable. The long-term outcomes and extraction experiences with F-CIEDs, in particular complex F-CIED (ICD/CRT devices), remain poorly understood., Methods: Patients referred for F-CIEDs implantation between 2002 and 2019 at two tertiary centers were included. Early complications were defined as ≤30 days following implant and late complications >30 days., Results: Thirty-one patients (66% male; age 56 ± 20 years; 35% [11] patients with congenital heart disease) were implanted with F-CIEDs (10 ICD/CRT and 21 pacemakers). Early complications were observed in 6.5% of patients: two lead displacements. Late complications at 6.8 ± 4.4 years occurred in 29.0% of patients. This was higher with complex F-CIED compared to simple F-CIED (60.0% vs. 14.3%, p = .02). Late complications were predominantly generator site related (n = 8, 25.8%) including seven infections/erosions and one generator migration. Eight femoral generators and 14 leads (median duration in situ seven [range 6-11] years) were extracted without complication., Conclusions: Procedural success with F-CIEDs is high with clinically acceptable early complication rates. There is a notable risk of late complications, particularly involving the generator site of complex devices following repeat femoral procedures. Extraction of chronic F-CIED in experienced centers is feasible and safe., (© 2022 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Background: A novel aggregated multiposition noncontact mapping (AMP-NCM) algorithm is proposed to diagnose cardiac arrhythmias., Objective: The purpose of this study was to computationally determine an accuracy threshold and to compare the accuracy and clinical utility of AMP-NCM to gold standard contact mapping., Methods: In a cellular automata model, the number of catheter positions and chamber coverage were varied to establish accuracy requirements for clinically relevant AMP-NCM. This guided the clinical study protocol. In a prospective cohort of patients with atrial tachycardia (AT), noncontact mapping (NCM) recordings from a single position (SP) and multiple positions were compared to contact mapping with a high-density multipolar catheter using morphology and timing differences of reconstructed signals. Identification of AT mechanisms and ablation targets using both AMP-NCM and contact mapping were randomly evaluated by 5 blinded reviewers., Results: AMP-NCM accuracy was asymptotic at 60 catheter positions in computational modeling. Twenty patients (age 65 ± 12 years; 19 male) with 26 ATs (5 focal, 21 reentrant) were studied. Morphologic correlation of signals derived from AMP-NCM was significantly better than those from SP-NCM compared to contact signals (median 0.93 vs 0.76; P <.001). AMP-NCM generated maps more rapidly than contact mapping (3 ± 1 minutes vs 13 ± 6 minutes; P <.001) and correctly diagnosed AT mechanisms in 25 of 26 maps (96%). Overall, 80% of arrhythmia mechanisms were correctly identified using AMP-NCM by blinded reviewers., Conclusion: Once 60 catheter positions were achieved, AMP-NCM successfully diagnosed mechanisms of AT and identified treatment sites equal to gold standard contact mapping in 3 minutes of procedural time., (Copyright © 2021 Heart Rhythm Society. All rights reserved.)

Background: The emergence of COVID-19 resulted in postponement of nonemergent surgical procedures for cardiac patients in London. mHealth represented a potentially viable mechanism for highlighting deteriorating patients on the lengthened cardiac surgical waiting lists., Objective: To evaluate the deployment of a digital health solution to support continuous triaging of patients on a cardiac surgical waiting list., Method: An NHS trust utilized an app-based mHealth solution (Huma Therapeutics) to help gather vital information on patients awaiting cardiac surgery (valvular and coronary surgery). Patients at a tertiary cardiac center on a waiting list for elective surgery were given the option to be monitored remotely via a mobile app until their date of surgery. Patients were asked to enter their symptoms once a week. The clinical team monitored this information remotely, prompting intervention for those patients who needed it., Results: Five hundred and twenty-five patients were on boarded onto the app. Of the 525 patients using the solution, 51 (9.71%) were identified as at risk of deteriorating based on data captured via the remote patient monitoring platform and subsequently escalated to their respective consultant. 81.7% of patients input at least one symptom after they were on boarded on the platform., Discussion: Although not a generalizable study, this change in practice clearly demonstrates the feasibility and potential benefit digital remote patient monitoring can have in triaging large surgical wait lists, ensuring those that need care urgently receive it. We recommend further study into the potential beneficial outcomes from preoperative cardiac mHealth solutions., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Medical Informatics Association.)

Background: The clinical effectiveness of ablating non-paroxysmal atrial fibrillation (non-PAF) relies on proper patient selection. We developed and validated a scoring system to predict non-PAF ablation outcomes., Methods: Data on 416 non-PAF ablations were analysed using binary logistic regression at a London centre. Identified preprocedural variables, which independently predicted freedom from atrial tachyarrhythmia. Twenty-one possible predictive variables and a model with c-statistic 0.751-explained outcome variation in London at mean follow-up 12±3 months. An additive point score (range 0-9) was developed-the FLAME score: female=1; long-lasting persistent atrial fibrillation=1; left atrial diameter in mm: 40 to <45 = 1, 45 to <50 = 2, 50 to <55=3, ≥55 =4; mitral regurgitation (MR) mild to moderate=1; extreme comorbidity=2. Extreme comorbidities include severe MR, moderate mitral stenosis, mitral replacement, hypertrophic cardiomyopathy or congenital heart disease., Results: The FLAME score was applied to data (882 non-PAF ablations) at a Californian centre, and predicted the outcome of both single (p<0.0001) and multiple (p<0.0001) procedures. For first ablation (follow-up 2.1 years (median, IQR 1.0-4.1)), FLAME score: 0-1 predicts 62% success, 2-4 44% and ≥5 29% (P trend <0.0001). After the final ablation (mean procedures: 1.4±0.6, follow-up 1.8 years (median, IQR 0.8-3.6)), FLAME score: 0-1 predicts 81% success, 2-4 65% and ≥5 44% (P trend <0.0001)., Conclusions: FLAME score is easily calculated, derived in London, and predicted single and multiple procedural outcomes for non-PAF ablations in California. In patients with a high score, even multiple procedures are usually ineffective., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Anatomical studies demonstrate significant variation in cavotricuspid isthmus (CTI) architecture., Methods: Thirty-eight patients underwent CTI ablation at two tertiary centers. Operators delivered 682 lesions with a target ablation index (AI) of 600 Wgs. Ablation parameters were recorded every 10-20 ms. Post hoc, Visitags were trisected according to CTI position: inferior vena cava (IVC), middle (Mid), or ventricular (V) lesions., Results: There were no complications. 92.1% of patients (n = 35) remained in sinus rhythm after 14.6 ± 3.4 months. For the whole CTI, peak AI correlated with mean impedance drop (ID) (R 2  = 0.89, p < .0001). However, analysis by anatomical site demonstrated a non-linear relationship Mid CTI (R 2  = 0.15, p = .21). Accordingly, while mean AI was highest Mid CTI (IVC: 473.1 ± 122.1 Wgs, Mid: 539.6 ± 103.5 Wgs, V: 486.2 ± 111.8 Wgs, ANOVA p < .0001), mean ID was lower (IVC: 10.7 ± 7.5Ω, Mid: 9.0 ± 6.5Ω, V: 10.9 ± 7.3Ω, p = .011), and rate of ID was slower (IVC: 0.37 ± 0.05 Ω/s, Mid: 0.18 ± 0.08 Ω/s, V: 0.29 ± 0.06 Ω/s, p < .0001). Mean contact force was similar at all sites; however, temporal fluctuations in contact force (IVC: 19.3 ± 12.0 mg/s, Mid: 188.8 ± 92.1 mg/s, V: 102.8 ± 32.3 mg/s, p < .0001) and catheter angle (IVC: 0.42°/s, Mid: 3.4°/s, V: 0.28°/s, p < .0001) were greatest Mid CTI. Use of a long sheath attenuated these fluctuations and improved energy delivery., Conclusions: Ablation characteristics vary across the CTI. At the Mid CTI, higher AI values do not necessarily deliver more effective ablation; this may reflect localized fluctuations in catheter angle and contact force., (© 2021 The Authors. Pacing and Clinical Electrophysiology published by Wiley Periodicals LLC.)

Background: Noncontact charge-density mapping allows rapid real-time global mapping of atrial fibrillation (AF), offering the opportunity for a personalized ablation strategy., Objective: The purpose of this study was to compare the 2-year outcome of an individualized strategy consisting of pulmonary vein isolation (PVI) plus core-to-boundary ablation (targeting the conduction pattern core with an extension to the nearest nonconducting boundary) guided by charge-density mapping, with an empirical PVI plus posterior wall electrical isolation (PWI) strategy., Methods: Forty patients (age 62 ± 12 years; 29 male) with persistent AF (10 ± 5 months) prospectively underwent charge-density mapping-guided PVI, followed by core-to-boundary stepwise ablation until termination of AF or depletion of identified cores. Freedom from AF/atrial tachycardia (AT) at 24 months was compared with a propensity score-matched control group of 80 patients with empirical PVI + PWI guided by conventional contact mapping., Results: Acute AF termination occurred in 8 of 40 patients after charge-density mapping-guided PVI alone and in 21 of the remaining 32 patients after core-to-boundary ablation in the study cohort, compared with 8 of 80 (10%) in the control cohort (P <.001). On average, 2.2 ± 0.6 cores were ablated post-PVI before acute AF termination. At 24 months, freedom from AF/AT after a single procedure was 68% in the study group vs 46% in the control group (P = .043)., Conclusion: An individualized ablation strategy consisting of PVI plus core-to-boundary ablation guided by noncontact charge-density mapping is a feasible and effective strategy for treating persistent AF, with a favorable 24-month outcome., (Crown Copyright © 2021. Published by Elsevier Inc. All rights reserved.)

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 < 13.6% reduction in the DF of the LApos following the stepwise ablation, the addition of LAAEI was associated with an increased restoration of sinus rhythm (55%, p < .05)., Conclusion: LAAEI in addition to stepwise ablation results in further reduction of the DF in the LApos, which is associated with acute termination of AF and favorable ablation outcome., (© 2020 Wiley Periodicals LLC.)

Aims: Long-standing persistent atrial fibrillation (LSPAF) is challenging to treat with suboptimal catheter ablation (CA) outcomes. Thoracoscopic surgical ablation (SA) has shown promising efficacy in atrial fibrillation (AF). This multicentre randomized controlled trial tested whether SA was superior to CA as the first interventional strategy in de novo LSPAF., Methods and Results: We randomized 120 LSPAF patients to SA or CA. All patients underwent predetermined lesion sets and implantable loop recorder insertion. Primary outcome was single procedure freedom from AF/atrial tachycardia (AT) ≥30 s without anti-arrhythmic drugs at 12 months. Secondary outcomes included clinical success (≥75% reduction in AF/AT burden); procedure-related serious adverse events; changes in patients' symptoms and quality-of-life scores; and cost-effectiveness. At 12 months, freedom from AF/AT was recorded in 26% (14/54) of patients in SA vs. 28% (17/60) in the CA group [OR 1.128, 95% CI (0.46-2.83), P = 0.83]. Reduction in AF/AT burden ≥75% was recorded in 67% (36/54) vs. 77% (46/60) [OR 1.13, 95% CI (0.67-4.08), P = 0.3] in SA and CA groups, respectively. Procedure-related serious adverse events within 30 days of intervention were reported in 15% (8/55) of patients in SA vs. 10% (6/60) in CA, P = 0.46. One death was reported after SA. Improvements in AF symptoms were greater following CA. Over 12 months, SA was more expensive and provided fewer quality-adjusted life-years (QALYs) compared with CA (0.78 vs. 0.85, P = 0.02)., Conclusion: Single procedure thoracoscopic SA is not superior to CA in treating LSPAF. Catheter ablation provided greater improvements in symptoms and accrued significantly more QALYs during follow-up than SA., Clinical Trial Registration: ISRCTN18250790 and ClinicalTrials.gov: NCT02755688., (© The Author(s) 2020. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: The efficacy of catheter ablation for atrial fibrillation (AF) in patients with functional mitral regurgitation (MR) and left ventricular (LV) systolic dysfunction (LVSD) is not known. The aim of the study is to determine the efficacy of catheter ablation for AF in patients with functional MR and LVSD, and to validate its effects on the severity of MR and cardiac reverse remodeling. Methods: We performed a retrospective study of 54 patients with functional MR who underwent AF ablation, including 21 (38.9%) with LVSD and 33 (61.1%) with normal LV systolic function (LVF). The primary outcomes evaluated were freedom from recurrent atrial tachyarrhythmia (ATa), severity of MR, and left atrial (LA) and LV remodeling. Results: During a mean follow-up of 20.7 ± 16.8 months, freedom from recurrent ATa was not significantly different between patients with LVSD and those with normal LVF after the first ablation ( P = 0.301) and after multiple ablations ( P = 0.728). Multivariable predictors of recurrent ATa were AF duration [hazard ratio (HR) 1.12, 95% confidence interval (CI) 1.01-1.25; P = 0.039), previous stroke (HR 5.28, 95% CI 1.46-19.14; P = 0.011), and estimated glomerular filtration rate (HR 0.97, 95% CI 0.95-0.99; P = 0.012). Compared with baseline, there was a significant reduction in severity of MR ( P = 0.007), LA size ( P < 0.001) and LV end-systolic dimension ( P = 0.008), and improvement in the LV ejection fraction ( P = 0.001) after restoring sinus rhythm in patients with LVSD. Conclusion: Catheter ablation is a valid option for the treatment of AF in patients with functional MR and LVSD, even though multiple procedures may be required., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2020 Wu, Zaman, Yakupoglu, Vennela, Emily, Nabeela, Jarman, Haldar, Jones, Wajid, Shi, Chen, Markides and Wong.)

Background: Global simultaneous recording of atrial activation during atrial fibrillation (AF) can elucidate underlying mechanisms contributing to AF maintenance. A better understanding of these mechanisms may allow for an individualized ablation strategy to treat persistent AF. The study aims to characterize left atrial endocardial activation patterns during AF using noncontact charge-density mapping., Methods: Twenty-five patients with persistent AF were studied. Activation patterns were characterized into three subtypes: (i) focal with centrifugal activation (FCA); (ii) localized rotational activation (LRA); and (iii) localized irregular activation (LIA). Continuous activation patterns were analyzed and distributed in 18 defined regions in the left atrium., Results: A total of 144 AF segments with 1068 activation patterns were analyzed. The most common pattern during AF was LIA (63%) which consists of four disparate features of activation: slow conduction (45%), pivoting (30%), collision (16%), and acceleration (7%). LRA was the second-most common pattern (20%). FCA accounted for 17% of all activations, arising frequently from the pulmonary veins (PVs)/ostia. A majority of patients (24/25; 96%) showed continuous and highly dynamic patterns of activation comprising multiple combinations of FCA, LRA, and LIA, transitioning from one to the other without a discernible order. Preferential conduction areas were typically seen in the mid-anterior (48%) and lower-posterior (40%) walls., Conclusion: Atrial fibrillation is characterized by heterogeneous activation patterns identified in PV-ostia and non-PV regions throughout the LA at varying locations between individuals. Clinical implications of individualized ablation strategies guided by charge-density mapping need to be determined., (© 2020 The Authors. Journal of Arrhythmia published by John Wiley & Sons Australia, Ltd on behalf of the Japanese Heart Rhythm Society.)

Objectives: This study sought to validate the accuracy of noncontact electrograms against contact electrograms in the left atrium during sinus rhythm (SR) and atrial fibrillation (AF)., Background: Noncontact mapping offers the opportunity to assess global cardiac activation in the chamber of interest. A novel noncontact mapping system, which records intracardiac voltage to derive cellular charge sources (dipole density), allows real-time mapping of AF to guide ablation., Methods: Noncontact and contact unipolar electrogram pairs were recorded simultaneously from multiple locations. Morphology correlation and timing difference of reconstructed electrograms obtained from a noncontact catheter were compared with those from contact electrograms obtained from a contact catheter at the same endocardial locations., Results: A total of 796 electrogram pairs in SR and 969 electrogram pairs in AF were compared from 20 patients with persistent AF. The median morphology correlation and timing difference (ms) in SR was 0.85 (interquartile range [IQR]: 0.71 to 0.94) and 6.4 ms (IQR: 2.6 to 17.1 ms); in AF was 0.79 (IQR: 0.69 to 0.88) and 14.4 ms (IQR: 6.7 to 26.2 ms), respectively. The correlation was stronger and the timing difference was less when the radial distance (r) from the noncontact catheter center to the endocardium was ≤ 40 versus > 40 mm; 0.87 (IQR: 0.72 to 0.94) versus 0.73 (IQR: 0.56 to 0.88) and 5.7 ms (IQR: 2.6 to 15.4 ms) versus 15.1 ms (IQR: 4.1 to 27.7 ms); p < 0.01 when in SR; 0.81 (IQR: 0.69 to 0.89) versus 0.67 (IQR: 0.45 to 0.82) and 12.3 ms (IQR: 5.9 to 21.8 ms) versus 28.3 ms (IQR: 16.2 to 36.0 ms); p < 0.01 when in AF., Conclusions: This novel noncontact dipole density mapping system provides comparable reconstructed atrial electrogram measurements in SR or AF in human left atrium when the anatomical site of interest is ≤40 mm from the mapping catheter., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

For many years, the left atrial appendage (LAA) was considered a dormant embryological remnant; however, it is a structurally complex and functional organ that contributes to cardiac haemodynamic changes and volume homeostasis through both its contractile properties and neurohormonal peptide secretion. When dysfunctional, the LAA contributes to thrombogenesis and subsequent increased predisposition to cardioembolic events. Consequently, the LAA has gained much attention as a therapeutic target to lower this risk. In addition, attention has focused on the LAA in its role as an electrical trigger for atrial tachycardia and atrial fibrillation with ablation of the LAA to achieve electrical isolation showing promising results in the maintenance of sinus rhythm. This in-depth review explores the structure, physiology and pathophysiology of the LAA, as well as LAA intervention and their sequelae., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Importance: There is a need for better arrhythmic risk stratification in nonischemic dilated cardiomyopathy (DCM). Titin-truncating variants (TTNtvs) in the TTN gene are the most common genetic cause of DCM and may be associated with higher risk of arrhythmias in patients with DCM., Objective: To determine if TTNtv status is associated with the development of life-threatening ventricular arrhythmia and new persistent atrial fibrillation in patients with DCM and implanted cardioverter defibrillator (ICD) or cardiac resynchronization therapy defibrillator (CRT-D) devices., Design, Setting, and Participants: This retrospective, multicenter cohort study recruited 148 patients with or without TTNtvs who had nonischemic DCM and ICD or CRT-D devices from secondary and tertiary cardiology clinics in the United Kingdom from February 1, 2011, to June 30, 2016, with a median (interquartile range) follow-up of 4.2 (2.1-6.5) years. Exclusion criteria were ischemic cardiomyopathy, primary valve disease, congenital heart disease, or a known or likely pathogenic variant in the lamin A/C gene. Analyses were performed February 1, 2017, to May 31, 2017., Main Outcome and Measures: The primary outcome was time to first device-treated ventricular tachycardia of more than 200 beats/min or first device-treated ventricular fibrillation. Secondary outcome measures included time to first development of persistent atrial fibrillation., Results: Of 148 patients recruited, 117 adult patients with nonischemic DCM and an ICD or CRT-D device (mean [SD] age, 56.9 [12.5] years; 76 [65.0%] men; 106 patients [90.6%] with primary prevention indications) were included. Having a TTNtv was associated with a higher risk of receiving appropriate ICD therapy (shock or antitachycardia pacing) for ventricular tachycardia or fibrillation (hazard ratio [HR], 4.9; 95% CI, 2.2-10.7; P < .001). This association was independent of all covariates, including midwall fibrosis measured by late gadolinium enhancement on cardiac magnetic resonance images (adjusted HR, 8.3; 95% CI, 1.8-37.6; P = .006). Having a TTNtv was also associated with the risk of receiving a shock (HR, 3.6; 95% CI, 1.1-11.6; P = .03). Individuals with a TTNtv and fibrosis had a greater rate of receiving appropriate device therapy than those with neither (HR, 16.6; 95% CI, 3.5-79.3; P < .001). Having a TTNtv was also a risk factor for developing new persistent atrial fibrillation (HR, 3.9; 95% CI, 1.3-12.0; P = .01)., Conclusions and Relevance: Having a TTNtv was an important risk factor for clinically significant arrhythmia in patients with DCM and ICD or CRT-D devices. Having a TTNtv, especially in combination with midwall fibrosis confirmed with cardiovascular magnetic resonance imaging, may provide a risk stratification approach for evaluating the need for ICD therapy in patients with DCM. This hypothesis should be tested in larger studies.

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<0.001, 22.6 [12.2-29.8] versus 54.2 [51.1-61.6] cm 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 (<0.05 mV) and atrial volume were similar between groups. Acute success and freedom from arrhythmia recurrence were worse in group B (100% versus 77% 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.

Background: The objective of our study was to compare resource use and clinical outcomes among atrial fibrillation (AF) patients who underwent catheter ablation versus antiarrhythmic drug (AAD) treatment., Methods: A retrospective cohort design using the Clinical Practice Research Data-Hospital Episode Statistics linkage data from England (2008-2013) was used. Patients undergoing catheter ablation treatment for AF were indexed to the date of first procedure. AAD patients with at least two different AAD drugs were indexed to the first fill of the second AAD. Patients were matched using 1:1 propensity matching. Primary endpoints including inpatient and outpatient visits were compared between ablation and AAD cohorts in the 4 months-1 year period after index. Secondary endpoints including heart failure, stroke, cardioversion, mortality, and a composite outcome were compared for the 4 months-3 years post-index period in the two groups. Cox-proportional hazards models were estimated for clinical outcomes comparison., Results: A total of 558 patients were matched in the two groups for resource utilization comparison. The average number of cardiovascular (CV)-related outpatient visits in the 4-12 months post-index period were significantly lower in the ablation group versus the AAD group (1.76 vs 3.57, p < .0001). There was no significant difference in all-cause and CV-related inpatient visits and all-cause outpatient visits among the two groups. For secondary endpoints comparison, 615 matched patients in each group emerged. Ablation patients had 38% lower risk of heart failure (hazard ratio [HR] 0.62, p = 0.0318), 50% lower risk of mortality (HR 0.50, p = 0.0082), and 43% lower risk of experiencing a composite outcome (HR 0.57, p = 0.0009) as compared to AAD treatment cohort., Conclusion: AF ablation was associated with significantly lower CV-related outpatient visits, and lower risk of heart failure and mortality versus AAD therapy.

Background Mapping using a multipolar catheter with small and closely spaced electrodes has been shown to improve the validity of electrograms to identify endocardial critical sites of reentry isthmus and foci of earliest activation. However, the feasibility, safety, and clinical outcome of using such technology to guide epicardial ventricular tachycardia (VT) ablation has not been reported. Methods and Results Thirty-three consecutive patients from 5 high-volume centers were studied. These patients had 43 epicardial maps using a novel 64-pole mini-basket catheter to guide VT ablation. Activation maps with 17 832 points per map (interquartile range: 7621-32 497 points per map) were acquired in 11 patients with tolerated VT (7 focal, 4 reentry). Substrate maps with 40149 points per map (interquartile range: 20926-49391 points per map) were acquired in 30 patients. Local abnormal ventricular activities were consistently demonstrated at the substrate regions of interest. Epicardial ablation was performed in 31 of 33 patients, with acute VT termination in 10 of 11 patients (91%). Complete elimination of local abnormal ventricular activities was achieved in 25 of 31 patients. At a median follow-up of 10 months (interquartile range: 4-14 months), 64% (7/11) of patients who had acute termination of VT and 55% (11/20) of those who had substrate modification alone were free of VT. There was no immediate complication following epicardial procedure. Conclusions Epicardial VT ablation guided by a mini-basket catheter is feasible and safe. Complete reentry VT circuits and foci of earliest activation were identified in all inducible stable VT. The longer term clinical outcome of ablation guided by this novel mapping technology utilizing small and closely spaced electrodes will have to be determined with a larger study.

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.

Background: Atrial fibrillation is the commonest arrhythmia which raises the risk of heart failure, thromboembolic stroke, morbidity and death. Pharmacological treatments of this condition are focused on heart rate control, rhythm control and reduction in risk of stroke. Selective ablation of cardiac tissues resulting in isolation of areas causing atrial fibrillation is another treatment strategy which can be delivered by two minimally invasive interventions: percutaneous catheter ablation and thoracoscopic surgical ablation. The main purpose of this trial is to compare the effectiveness and safety of these two interventions., Methods/design: Catheter Ablation versus Thoracoscopic Surgical Ablation in Long Standing Persistent Atrial Fibrillation (CASA-AF) is a prospective, multi-centre, randomised controlled trial within three NHS tertiary cardiovascular centres specialising in treatment of atrial fibrillation. Eligible adults (n = 120) with symptomatic, long-standing, persistent atrial fibrillation will be randomly allocated to either catheter ablation or thoracoscopic ablation in a 1:1 ratio. Pre-determined lesion sets will be delivered in each treatment arm with confirmation of appropriate conduction block. All patients will have an implantable loop recorder (ILR) inserted subcutaneously immediately following ablation to enable continuous heart rhythm monitoring for at least 12 months. The devices will be programmed to detect episodes of atrial fibrillation and atrial tachycardia ≥ 30 s in duration. The patients will be followed for 12 months, completing appropriate clinical assessments and questionnaires every 3 months. The ILR data will be wirelessly transmitted daily and evaluated every month for the duration of the follow-up. The primary endpoint in the study is freedom from atrial fibrillation and atrial tachycardia at the end of the follow-up period., Discussion: The CASA-AF Trial is a National Institute for Health Research-funded study that will provide first-class evidence on the comparative efficacy, safety and cost-effectiveness of thoracoscopic surgical ablation and conventional percutaneous catheter ablation for long-standing persistent atrial fibrillation. In addition, the results of the trial will provide information on the effects on patients' quality of life., Trial Registration: ISRCTN Registry, ISRCTN18250790 . Registered on 24 April 2015.

Patients with atrial fibrillation (AF) are at increased risk of thrombotic events despite oral anticoagulation (OAC). Radiofrequency catheter ablation (RFCA) can restore and maintain sinus rhythm (SR) in patients with AF. To assess whether RFCA improves thrombotic status. 80 patients (71% male, 64 ± 12y) with recently diagnosed AF, on OAC and scheduled to undergo RFCA or DC cardioversion (DCCV) were recruited. Thrombotic status was assessed using the point-of-care global thrombosis test (GTT), before, and 4-6 weeks after DCCV and 3 months after RFCA. The GTT first measures the time taken for occlusive thrombus formation (occlusion time, OT), while the second phase of the test measures the time taken to spontaneously dissolve this clot through endogenous thrombolysis (lysis time, LT). 3 months after RFCA, there was a significant reduction in LT (1994s [1560; 2475] vs. 1477s [1015; 1878]) in those who maintained SR, but not in those who reverted to AF. At follow-up, LT was longer in those in AF compared to those in SR (AF 2966s [2038; 3879] vs. SR 1477s [1015; 1878]). RFCA resulted in no change in OT value, irrespective of rhythm outcome. Similarly, there was no change in OT or LT in response to DCCV, irrespective of whether SR was restored. Successful restoration and maintenance of SR following RFCA of AF is associated with improved global thrombotic status with enhanced fibrinolysis. Larger studies are required to confirm these early results and investigate whether improved thrombotic status translates into fewer thromboembolic events.

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., (Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.)

Aims: Initiating mechanisms of atrial fibrillation (AF) remain poorly understood, involving complex interaction between triggers and the atrial substrate. This study sought to classify the transitional phenomena, hypothesizing that there is consistency within and between patients in trigger-substrate interaction during transition to AF., Methods and Results: Non-contact left atrial (LA) mapping was performed in 17 patients undergoing ablation for paroxysmal AF. All had spontaneous ectopy. Left atrial activation from the first ectopic to established AF was examined offline to characterize the initiating and transitional sequence of activation. In 57 fully mapped spontaneous AF initiations in 8 patients, all involved interaction of pulmonary venous/LA triggers with a septopulmonary line of block (SP-LOB) also evident in sinus rhythm, by 4 different transitional mechanisms characterized by (i) continuous focal firing: AF resulted from fragmentation of each ectopic wavefront through gaps in the SP-LOB and persisted only while focal firing continued (n = 18/32%) (ii) transient focal firing, wavefront fragmentation at the SP-LOB produced wavelet re-entry that persisted after cessation of an initiating ectopic source (n = 12/21%), (iii) of two separate interacting ectopic foci (n = 15/26%), or from (iv) transiently stable macroreentry (n = 12/21%), around the SP-LOB extending to the LA roof, resulting in progressive wavefront fragmentation. It was found that 79 ± 22% of each of the initiations in individual patients showed the same triggering mechanism., Conclusion: Onset of paroxysmal AF can be described by discrete mechanistic categories, all involving interaction of ectopic activity with a common SP-LOB. Within/between-patient consistency of initiations suggests constancy of the interacting triggers and substrate, and supports the concept of mechanistically tailored treatment., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions please email: journals.permissions@oup.com.)

Background: The increased risk of brady- and tachy-arrhythmias in the congenital heart disease (CHD) population means that cardiac rhythm management devices are often required at an early age and expose patients to device-related complications. The present study drew upon four decades of experience at a tertiary adult congenital heart disease ACHD center and aimed to investigate the indication for cardiac implantable electronic devices (CIEDs) and predictors of late device-related complication requiring re-intervention., Methods: A retrospective review of pacing records of ACHD patients over forty years was carried out. The primary outcome measure was device related complication requiring re-intervention., Results: Between 1970 and 2009, 238 structural CHD patients who received CIEDs with follow-up data were identified (structural group). As a comparator group, 98 patients with congenital conduction disease or long QT syndrome with a structurally normal heart (electrical group) were included in the study. During a mean follow-up of 9.6±8.5years, 72 (21%) patients (44 structural group, 28 electrical group) required ≥1 re-intervention due to device related complications. Multivariate analysis showed that age at the time of device implant was an independent predictor of late device-related complications (HR 0.77, 95% CI 0.60-0.98, p=0.04). Sub-analysis of the structural group showed that ACHD complexity (Bethesda guideline) was the only predictor late device-related complication in the structural group (HR 2.96, 95% CI: 1.67-5.26, p<0.01)., Conclusion: Increasing age at device implant was inversely associated with late device-related complications. ACHD patients with complex anatomy are at increased risk of device-related complications at mid and long-term follow-up., (Copyright © 2017 Elsevier B.V. All rights reserved.)