Search

Aims: Using thermal-based energy sources [radiofrequency (RF) energy/cryo energy] for catheter ablation is considered effective and safe when performing pulmonary vein isolation (PVI) in patients with paroxysmal atrial fibrillation (AF). However, treatment success remains limited and complications can occur due to the propagation of thermal energy into non-target tissues. We aim to compare pulsed field ablation (PFA) with RF ablation in terms of efficacy and safety for patients with drug-resistant paroxysmal AF., Methods and Results: The BEAT PAROX-AF trial is a European multicentre, superiority, open-label randomized clinical trial in two parallel groups. A total of 292 participants were recruited in 9 high-volume European clinical centres in 5 countries. Patients with paroxysmal AF were randomized to PFA (FARAPULSE Endocardial Ablation System©, Boston Scientific) or RF using the CLOSE protocol with contact force sensing catheter (SmartTouch© catheter and CARTO© Biosense Webster). The primary endpoint will be the 1-year recurrence of atrial arrhythmia, and the major secondary safety endpoint will be the occurrence of acute (<7 days) procedure-related serious adverse events, or pulmonary vein stenosis, or atrio-oesophageal fistula up to 12 months. Additionally, five sub-studies investigate the effect of PFA on oesophageal safety, cerebral lesions, cardiac autonomic nervous system, durability of PVI as assessed during redo ablation procedures, and atrial and ventricular function. The study began on 27 December 2021 and concluded recruitment on 17 January 2024. Results will be available in mid-2025., Conclusion: The BEAT PAROX-AF trial aims to provide critical insights into the optimal treatment approach for patients with paroxysmal AF., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Although the mechanism of an atrial tachycardia (AT) can usually be elucidated using modern high-resolution mapping systems, it would be helpful if the AT mechanism and circuit could be predicted before initiating mapping., Objective: We examined if the information gathered from the cycle length (CL) of the tachycardia can help predict the AT-mechanism and its localization., Methods: One hundred and thirty-eight activation maps of ATs including eight focal-ATs, 94 macroreentrant-ATs, and 36 localized-ATs in 95 patients were retrospectively reviewed. Maximal CL (MCL) and minimal CL (mCL) over a minute period were measured via a decapolar catheter in the coronary sinus. CL-variation and beat-by-beat CL-alternation were examined. Additionally, the CL-respiration correlation was analysed by the RhythmiaTM system. : Both MCL and mCL were significantly shorter in macroreentrant-ATs [MCL = 288 (253-348) ms, P = 0.0001; mCL = 283 (243-341) ms, P = 0.0012], and also shorter in localized-ATs [MCL = 314 (261-349) ms, P = 0.0016; mCL = 295 (248-340) ms, P = 0.0047] compared to focal-ATs [MCL = 506 (421-555) ms, mCL = 427 (347-508) ms]. An absolute CL-variation (MCL-mCL) < 24 ms significantly differentiated re-entrant ATs from focal-ATs with a sensitivity = 96.9%, specificity = 100%, positive predictive value (PPV) = 100%, and negative predictive value (NPV) = 66.7%. The beat-by-beat CL-alternation was observed in 10/138 (7.2%), all of which showed the re-entrant mechanism, meaning that beat-by-beat CL-alternation was the strong sign of re-entrant mechanism (PPV = 100%). Although the CL-respiration correlation was observed in 28/138 (20.3%) of ATs, this was predominantly in right-atrium (RA)-ATs (24/41, 85.7%), rather than left atrium (LA)-ATs (4/97, 4.1%). A positive CL-respiration correlation highly predicted RA-ATs (PPV = 85.7%), and negative CL-respiration correlation probably suggested LA-ATs (NPV = 84.5%)., Conclusion: Detailed analysis of the tachycardia CL helps predict the AT-mechanism and the active AT chamber before an initial mapping., Competing Interests: Conflict of interest: Drs Haïssaguerre, Hocini, Jaïs, Martin, and Sacher have received lecture fees from Biosense Webster. Drs Haïssaguerre, Hocini, Jaïs, and Sacher have received lecture fees and Takigawa has received speaking honoraria from Abbott. Drs Derval, Jaïs, Martin, and Sacher have received speaking honoraria and consulting fees from Boston Scientific. All remaining authors have declared no conflicts of interest., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Assess prevalence, risk factors, and management of patients with intra-cardiac thrombus referred for scar-related ventricular tachycardia (VT) ablation., Methods and Results: Consecutive VT ablation referrals between January 2015 and December 2019 were reviewed (n = 618). Patients referred for de novo, scar-related VT ablation who underwent pre-procedure cardiac computed tomography (cCT) were included. We included 401 patients [61 ± 14 years; 364 male; left ventricular ejection fraction (LVEF) 40 ± 13%]; 45 patients (11%) had cardiac thrombi on cCT at 49 sites [29 LV; eight left atrial appendage (LAA); eight right ventricle (RV); four right atrial appendage]. Nine patients had pulmonary emboli. Overall predictors of cardiac thrombus included LV aneurysm [odds ratio (OR): 6.6, 95%, confidence interval (CI): 3.1-14.3], LVEF < 40% (OR: 3.3, CI: 1.5-7.3), altered RV ejection fraction (OR: 2.3, CI: 1.1-4.6), and electrical storm (OR: 2.9, CI: 1.4-6.1). Thrombus location-specific analysis identified LV aneurysm (OR: 10.9, CI: 4.3-27.7) and LVEF < 40% (OR: 9.6, CI: 2.6-35.8) as predictors of LV thrombus and arrhythmogenic right ventricular cardiomyopathy (OR: 10.6, CI: 1.2-98.4) as a predictor for RV thrombus. Left atrial appendage thrombi exclusively occurred in patients with atrial fibrillation. Ventricular tachycardia ablation was finally performed in 363 including 7 (16%) patients with thrombus but refractory electrical storm. These seven patients had tailored ablation with no embolic complications. Only one (0.3%) ablation-related embolic event occurred in the entire cohort., Conclusion: Cardiac thrombus can be identified in 11% of patients referred for scar-related VT ablation. These findings underscore the importance of systematic thrombus screening to minimize embolic risk., Competing Interests: Conflict of interest: S.M. received speaking honoraria and consulting fees from Biosense Webster and Abbott. P.J. received speaking honorarium and consulting fees from Biosense Webster, Boston Scientific, and Farapulse. He is stakeholder for Inheart. H.C. is stakeholder for Inheart. F.S. received speaking honorarium and consulting fees from Inheart, Biosense Webster, Boston Scientific, and Abbott., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Society of Cardiology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Aims: Pulsed field ablation (PFA), a non-thermal ablative modality, may show different effects on the myocardial tissue compared to thermal ablation. Thus, this study aimed to compare the left atrial (LA) structural and mechanical characteristics after PFA vs. thermal ablation., Methods and Results: Cardiac magnetic resonance was performed pre-ablation, acutely (<3 h), and 3 months post-ablation in 41 patients with paroxysmal atrial fibrillation (AF) undergoing pulmonary vein (PV) isolation with PFA (n = 18) or thermal ablation (n = 23, 16 radiofrequency ablations, 7 cryoablations). Late gadolinium enhancement (LGE), T2-weighted, and cine images were analysed. In the acute stage, LGE volume was 60% larger after PFA vs. thermal ablation (P < 0.001), and oedema on T2 imaging was 20% smaller (P = 0.002). Tissue changes were more homogeneous after PFA than after thermal ablation, with no sign of microvascular damage or intramural haemorrhage. In the chronic stage, the majority of acute LGE had disappeared after PFA, whereas most LGE persisted after thermal ablation. The maximum strain on PV antra, the LA expansion index, and LA active emptying fraction declined acutely after both PFA and thermal ablation but recovered at the chronic stage only with PFA., Conclusion: Pulsed field ablation induces large acute LGE without microvascular damage or intramural haemorrhage. Most LGE lesions disappear in the chronic stage, suggesting a specific reparative process involving less chronic fibrosis. This process may contribute to a preserved tissue compliance and LA reservoir and booster pump functions., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Extra-atrial injury can cause complications after catheter ablation for atrial fibrillation (AF). Pulsed field ablation (PFA) has generated preclinical data suggesting that it selectively targets the myocardium. We sought to characterize extra-atrial injuries after pulmonary vein isolation (PVI) between PFA and thermal ablation methods., Methods and Results: Cardiac magnetic resonance (CMR) imaging was performed before, acutely (<3 h) and 3 months post-ablation in 41 paroxysmal AF patients undergoing PVI with PFA (N = 18, Farapulse) or thermal methods (N = 23, 16 radiofrequency, 7 cryoballoon). Oesophageal and aortic injuries were assessed by using late gadolinium-enhanced (LGE) imaging. Phrenic nerve injuries were assessed from diaphragmatic motion on intra-procedural fluoroscopy. Baseline CMR showed no abnormality on the oesophagus or aorta. During ablation procedures, no patient showed phrenic palsy. Acutely, thermal methods induced high rates of oesophageal lesions (43%), all observed in patients showing direct contact between the oesophagus and the ablation sites. In contrast, oesophageal lesions were observed in no patient ablated with PFA (0%, P < 0.001 vs. thermal methods), despite similar rates of direct contact between the oesophagus and the ablation sites (P = 0.41). Acute lesions were detected on CMR on the descending aorta in 10/23 (43%) after thermal ablation, and in 6/18 (33%) after PFA (P = 0.52). CMR at 3 months showed a complete resolution of oesophageal and aortic LGE in all patients. No patient showed clinical complications., Conclusion: PFA does not induce any signs of oesophageal injury on CMR after PVI. Due to its tissue selectivity, PFA may improve safety for catheter ablation of AF., (© The Author(s) 2021. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Aims: Electrocardiographic imaging (ECGI) is a promising tool to map the electrical activity of the heart non-invasively using body surface potentials (BSP). However, it is still challenging due to the mathematically ill-posed nature of the inverse problem to solve. Novel approaches leveraging progress in artificial intelligence could alleviate these difficulties., Methods and Results: We propose a deep learning (DL) formulation of ECGI in order to learn the statistical relation between BSP and cardiac activation. The presented method is based on Conditional Variational AutoEncoders using deep generative neural networks. To quantify the accuracy of this method, we simulated activation maps and BSP data on six cardiac anatomies.We evaluated our model by training it on five different cardiac anatomies (5000 activation maps) and by testing it on a new patient anatomy over 200 activation maps. Due to the probabilistic property of our method, we predicted 10 distinct activation maps for each BSP data. The proposed method is able to generate volumetric activation maps with a good accuracy on the simulated data: the mean absolute error is 9.40 ms with 2.16 ms standard deviation on this testing set., Conclusion: The proposed formulation of ECGI enables to naturally include imaging information in the estimation of cardiac electrical activity from BSP. It naturally takes into account all the spatio-temporal correlations present in the data. We believe these features can help improve ECGI results., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

Aims: We hypothesized that an epicardial approach using ethanol infusion in the vein of Marshall (EIVOM) may improve the result of ablation for perimitral flutter (PMF)., Methods and Results: We studied 103 consecutive patients with PMF undergoing high-resolution mapping. The first 71 were treated with radiofrequency (RF) ablation alone (RF-group), and the next 32 underwent EIVOM followed by RF on the endocardial and epicardial mitral isthmus (EIVOM/RF-group). Contact force was not measured during ablation. Acute and 1-year outcomes were compared. Flutter termination rates were similar between the RF-group (63/71, 88.7%) and EIVOM/RF-group (31/32, 96.8%, P = 0.27). Atrial tachycardia (AT) terminated with EIVOM alone in 22/32 (68.6%) in the EIVOM/RF-group. Bidirectional block of mitral isthmus was always achieved in the EIVOM/RF-group, but significantly less frequently achieved in the RF-group (62/71, 87.3%; P = 0.05). Median RF duration for AT termination/conversion was shorter [0 (0-6) s in the EIVOM/RF-group than 312 (55-610) s in the RF-group, P < 0.0001], as well as for mitral isthmus block in the EIVOM/RF-group [246 (0-663) s] than in the RF-group [900 (525-1310) s, P < 0.0001]. Pericardial effusion was observed in 1/32 (3.2%) in EIVOM/RF-group and 5/71 (7.0%) in RF-group (P = 0.66); two in RF-group required drainage and one of them developed subsequent ischaemic stroke. One-year follow-up demonstrated fewer recurrences in the EIVOM/RF-group [6/32 (18.8%)] than in the RF-group [29/71 (40.8%), P = 0.04]. By multivariate analysis, only EIVOM was significantly associated with less AT recurrence (hazard ratio = 0.35, P = 0.018)., Conclusion: Ethanol infusion in the vein of Marshall may reduce RF duration required for PMF termination as well as for mitral isthmus block without severe complications, and the mid-term outcome may be improved by this approach., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com.)

Aims: Atrial fibrosis contributes to arrhythmogenesis in atrial fibrillation and can be detected by MRI or electrophysiological mapping. The current study compares the spatial correlation between delayed enhancement (DE) areas to low-voltage areas (LVAs) and to arrhythmogenic areas with spatio-temporal dispersion (ST-Disp) or continuous activity (CA) in atrial fibrillation (AF)., Methods and Results: Sixteen patients with persistent AF (nine long-standing) underwent DE-magnetic resonance imaging (1.25 mm × 1.25 mm × 2.5 mm) prior to pulmonary vein isolation. Left atrial (LA) voltage mapping was acquired in AF and the regional activation patterns of 7680 AF wavelets were analysed. Sites with ST-Disp or CA were characterized (voltage, duration) and their spatial relationship to DE areas and LVAs <0.5 mV was assessed. Delayed enhancement areas and LVAs covered 55% and 24% (P < 0.01) of total LA surface, respectively. Delayed enhancement area was present at 61% of LVAs, whereas low voltage was present at 28% of DE areas. Most DE areas (72%) overlapped with atrial high-voltage areas (>0.5 mV). Spatio-temporal dispersion and CA more frequently co-localized with LVAs than with DE areas (78% vs. 63%, P = 0.02). Regional bipolar voltage of ST-Disp vs. CA was 0.64 ± 0.47 mV vs. 0.58 ± 0.51 mV. All 28 ST-Disp and 56 CA areas contained electrograms with prolonged duration (115 ± 14 ms) displaying low voltage (0.34 ± 0.11 mV)., Conclusion: A small portion of DE areas and LVAs harbour the arrhythmogenic areas displaying ST-Disp or CA. Most arrhythmogenic activities co-localized with LVAs, while there was less co-localization with DE areas. There is an important mismatch between DE areas and LVAs which needs to be considered when used as target for catheter ablation., (Published on behalf of the European Society of Cardiology. All rights creserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Successful mapping and ablation of ventricular tachycardias remains a challenging clinical task. Whereas conventional entrainment and activation mapping was for many years the gold standard to identify reentrant circuits in ischaemic ventricular tachycardia ablation procedures, substrate mapping has become the cornerstone of ventricular tachycardia ablation. In the last decade, technology has dramatically improved. In parallel to high-density automated mapping, cardiac imaging and image integration tools are increasingly used to assess the structural ventricular tachycardia substrate. The aim of this review is to describe the technologies underlying these new mapping systems and to discuss their possible role in providing new insights into identification and visualization of reentrant tachycardia mechanisms., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2019. For permissions, please email: journals.permissions@oup.com.)

Aims: Clinical application of patient-specific cardiac computer models requires fast and robust processing pipelines that can be seamlessly integrated into clinical workflows. We aim at building such a pipeline from computed tomography (CT) images to personalized cardiac electrophysiology (EP) model. The simulation output could be useful in the context of post-infarct ventricular tachycardia (VT) radiofrequency ablation (RFA) planning for pre-operative targets prediction., Methods and Results: The support for model personalization is a patient-specific virtual three-dimensional heart obtained from CT images. Here, the scar is identified as thinning of the myocardial wall on automatically computed thickness maps. We then use an Eikonal model of wave front propagation with reduced velocity in the damaged areas. An image-based vessel enhancement algorithm can automatically identify VT isthmuses. The personalized model is used for virtual pacing. We obtained a very fast pipeline that enables simulations in only a few minutes. It is fully automated starting from the semi-automated image segmentation phase. The computational time frame is compatible with the construction of a virtual pacing tool. In this tool, onset points and an optional directional block could be interactively selected. The directional block is a simple way to model tissue refractoriness. Output activation maps are compared with EP data acquired pre-operatively. We show that this framework allows the reproduction of recorded re-entrant VT activation patterns., Conclusion: Our simulation framework has an application in VT RFA intervention planning. It could be used to guide EP explorations and even predict ablation targets pre-operatively. This could reduce intervention duration and improve success rate.

Aims: Treatments for persistent atrial fibrillation (AF) offer limited efficacy. One potential strategy aims to return the right atrium (RA) to sinus rhythm (SR) by ablating interatrial connections (IAC) to isolate the atria, but there is limited clinical data to evaluate this ablation approach. We aimed to use simulation to evaluate and predict patient-specific suitability for ablation of IAC to treat AF., Methods and Results: Persistent AF was simulated in 12 patient-specific geometries, incorporating electrophysiological heterogeneity and fibres, with IAC at Bachmann's bundle, the coronary sinus, and fossa ovalis. Simulations were performed to test the effect of left atrial (LA)-to-RA frequency gradient and fibrotic remodelling on IAC ablation efficacy. During AF, we simulated ablation of one, two, or all three IAC, with or without pulmonary vein isolation and determined if this altered or terminated the arrhythmia. For models without structural remodelling, ablating all IAC terminated RA arrhythmia in 83% of cases. Models with the LA-to-RA frequency gradient removed had an increased success rate (100% success). Ablation of IACs is less effective in cases with fibrotic remodelling (interstitial fibrosis 50% success rate; combination remodelling 67%). Mean number of phase singularities in the RA was higher pre-ablation for IAC failure (success 0.6 ± 0.8 vs. failure 3.2 ± 2.5, P < 0.001)., Conclusion: This simulation study predicts that IAC ablation is effective in returning the RA to SR for many cases. Patient-specific modelling approaches have the potential to stratify patients prior to ablation by predicting if drivers are located in the LA or RA. We present a platform for predicting efficacy and informing patient selection for speculative treatments.

Aims: Cardiac magnetic resonance (CMR) is recommended as a second-line method to diagnose ventricular arrhythmia (VA) substrate. We assessed the diagnostic yield of CMR including high-resolution late gadolinium-enhanced (LGE) imaging., Methods and Results: Consecutive patients with sustained ventricular tachycardia (VT), non-sustained VT (NSVT), or ventricular fibrillation/aborted sudden death (VF/SCD) underwent a non-CMR diagnostic workup according to current guidelines, and CMR including LGE imaging with both a conventional breath-held and a free-breathing method enabling higher spatial resolution (HR-LGE). The diagnostic yield of CMR was compared with the non-CMR workup, including the incremental value of HR-LGE. A total of 157 patients were enrolled [age 54 ± 17 years; 75% males; 88 (56%) sustained VT, 52 (33%) NSVT, 17 (11%) VF/SCD]. Of these, 112 (71%) patients had no history of structural heart disease (SHD). All patients underwent electrocardiography and echocardiography, 72% coronary angiography, and 51% exercise testing. Pre-CMR diagnoses were 84 (54%) no SHD, 39 (25%) ischaemic cardiomyopathy (ICM), 11 (7%) non-ischaemic cardiomyopathy (NICM), 3 (2%) arrhythmogenic right ventricular cardiomyopathy (ARVC), 2 (1%) hypertrophic cardiomyopathy (HCM), and 18 (11%) other. CMR modified these diagnoses in 48 patients (31% of all and 43% of those with no SHD history). New diagnoses were 9 ICM, 28 NICM, 8 ARVC, 1 HCM, and 2 other. CMR modified therapy in 19 (12%) patients. In patients with no SHD after non-CMR tests, SHD was found in 32 of 84 (38%) patients. Eighteen of these patients showed positive HR-LGE and negative conventional LGE. Thus, HR-LGE significantly increased the CMR detection of SHD (17-38%, P < 0.001)., Conclusion: CMR including HR-LGE imaging has high diagnostic value in patients with VAs. This has major prognostic and therapeutic implications, particularly in patients with negative pre-CMR workup.

Aims: To compare the arrhythmic response to isoproterenol and exercise testing in newly diagnosed arrhythmogenic right ventricular cardiomyopathy (ARVC) patients., Methods and Results: We studied isoproterenol [continuous infusion (45 µg/min) for 3 min] and exercise testing (workload increased by 30 W every 3 min) performed in consecutive newly diagnosed ARVC patients. Both tests were evaluated with regard to the incidence of (i) polymorphic premature ventricular contractions (PVCs) and couplet(s) or (ii) sustained or non-sustained ventricular tachycardia (VT) with left bundle branch block [excluding right ventricular outflow tract VT]; and compared to a control group referred for the evaluation of PVCs without structural heart disease. Thirty-seven ARVC patients (63.5% male, age 38 ± 16 years) were included. The maximal sinus rhythm heart rate achieved during isoproterenol testing was significantly lower compared to exercise testing (149 ± 17 bpm vs. 166 ± 19 bpm, P < 0.0001). However, the incidence of polymorphic ventricular arrhythmias was much higher during isoproterenol testing compared to exercise testing [33/37 (89.2%) vs. 16/37 (43.2%), P < 0.0001]. Interestingly, isoproterenol testing was arrhythmogenic in all 15 patients in whom baseline PVCs were reduced or suppressed during exercise testing. During both isoproterenol and exercise testing, control group presented a low incidence of ventricular arrhythmias compared to ARVC patients (8.1% vs. 89.2%, P < 0.0001 and 2.7% vs. 43.2%, P < 0.0001, respectively)., Conclusions: The incidence of polymorphic ventricular arrhythmias is significantly higher during isoproterenol compared to exercise testing in newly diagnosed ARVC patients, suggesting its potential utility for the diagnosis.

Aims: Catheter ablation is an effective technique for terminating atrial arrhythmia. However, given a high atrial fibrillation (AF) recurrence rate, optimal ablation strategies have yet to be defined. Computer modelling can be a powerful aid but modelling of fibrosis, a major factor associated with AF, is an open question. Several groups have proposed methodologies based on imaging data, but no comparison to determine which methodology best corroborates clinically observed reentrant behaviour has been performed. We examined several methodologies to determine the best method for capturing fibrillation dynamics., Methods and Results: Patient late gadolinium-enhanced magnetic resonance imaging data were transferred onto a bilayer atrial computer model and used to assign fibrosis distributions. Fibrosis was modelled as conduction disturbances (lower conductivity, edge splitting, or percolation), transforming growth factor-β1 ionic channel effects, myocyte-fibroblast coupling, and combinations of the preceding. Reentry was induced through pulmonary vein ectopy and the ensuing rotor dynamics characterized. Non-invasive electrocardiographic imaging data of the patients in AF was used for comparison. Electrograms were computed and the fractionation durations measured over the surface. Edge splitting produced more phase singularities from wavebreaks than the other representations. The number of phase singularities seen with percolation was closer to the clinical values. Addition of fibroblast coupling had an organizing effect on rotor dynamics. Simple tissue conductivity changes with ionic changes localized rotors over fibrosis which was not observed with clinical data., Conclusion: The specific representation of fibrosis has a large effect on rotor dynamics and needs to be carefully considered for patient specific modelling., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For Permissions, please email: journals.permissions@oup.com.)

Aims: Ventricular tachycardia (VT) ablation for ventricular arrhythmias is a validated approach, typically performed endocardially, or combined with an epicardial approach if endocardial ablation failed or in case of non-ischaemic cardiomyopathy. We report our experience with epicardial only procedure in a subset of patients with incessant VT or VT storm., Methods and Results: This was a single centre retrospective study. Between 2011 and 2014, all patients referred for VT ablation were reviewed at CHU Bordeaux. All patients with an epicardial only (anterior percutaneous approach) mapping and ablation procedure were included. In total, 296 patients underwent a VT ablation and 4 (all male, 70 ± 7 years, 27 ± 11% left ventricular ejection fraction) of them underwent an epicardial only procedure: two ischaemic patients had an endocardial left ventricular thrombus and incessant VT. One patient post-myocarditis had a failed a previous endocardial procedure without local abnormal ventricular activity (LAVA). The fourth patient had a dilated cardiomyopathy and a complicated epicardial puncture followed by mild continuous bleeding (200 mL) precluding anticoagulation associated with left ventricular endocardial access. Local abnormal ventricular activity elimination was verified only epicardially in all and obtained in two patients and non-inducibility was tested and achieved in the two patients without thrombus. No further complications occurred. After a mean follow-up of 21 ± 12 months, one patient (25%) had recurrence of VT and no patient death was observed., Conclusion: Epicardial only ablation seems feasible and effective and useful in a limited subset of patients with incessant VT. However, endpoints are more difficult to evaluate and long-term follow-up is needed., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.)

Aims: Atrial numerical modelling has generally represented the organ as either a surface or tissue with thickness. While surface models have significant computational advantages over tissue models, they cannot fully capture propagation patterns seen in vivo, such as dissociation of activity between endo- and epicardium. We introduce an intermediate representation, a bilayer model of the human atria, which is capable of recreating recorded activation patterns., Methods and Results: We simultaneously solved two surface monodomain problems by formalizing an optimization method to set a coupling term between them. Two different asymptotically equivalent numerical implementations of the model are presented. We then built a geometrically and electrophysiologically detailed model of the human atria based on CT data, including two layers of fibre directions, major muscle bundles, and discrete atrial coupling. We adjusted parameters to recreate clinically measured activation times. Activation was compared with a monolayer model. Activation was fit to the physiological range measured over the entire atria. The crista terminalis and pectinate muscles were important for local right atrial activation, but did not significantly affect total activation time. Propagation in the bilayer model was similar to that of a monolayer, but with noticeable difference, due to three-dimensional propagation where fibre direction changed abruptly across the wall, resulting in a slight dissociation of activity., Conclusion: Atrial structure plays the dominant role in determining activation. A bilayer model is able to take into account transmural heterogeneities, while maintaining the low computational load associated with surface models., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)

Aims: Pulmonary vein isolation (PVI) is the mainstay of interventional treatment of paroxysmal atrial fibrillation (PAF). We report on the feasibility and efficacy of a novel, open-irrigated mapping and radiofrequency (RF) ablation catheter., Methods and Results: Thirty-nine consecutive patients (pts; age 60 ± 10 years, 8 females) suffering from drug-refractory PAF referred for PVI were included in this prospective study. Pulmonary vein isolation was performed with the use of a novel 10-pole circular, open-irrigated mapping and ablation catheter (nMARQ, Biosense Webster). Outcome parameters were the acute success rate in establishing complete PVI and the rate of sustained sinus rhythm (SR) during follow-up (FU). Ten patients underwent a repeat procedure for recurrent AF. Ninety-eight percent of the PVs could be acutely isolated using solely the nMARQ catheter by applying a mean total of 10.0 ± 4.6 min of RF energy. The mean total procedure duration was 86 ± 29 min, and the mean fluoroscopy time was 22.2 ± 6.5 min, respectively. Transient reconnection provoked by adenosine was observed in 10 of 24 patients, most frequently in the right superior PV. Cardiac tamponade related to transseptal puncture occurred in one patient. Reconnected PVs could be identified as a source of recurrent AF in 9 of 10 patients undergoing a repeat procedure. Single and multiple procedure success rates during a mean FU of 140 ± 75 days were 66 and 77%, respectively., Conclusion: Irrigated multi-electrode RF ablation is fast and effective, providing a high rate of isolated PVs without the need of touch-up lesions. Success rates were comparable with other techniques with a low complication rate. Recurrences of AF were mainly due to recovered pulmonary vein/left atrium conduction., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)