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Background: Treatment options for high-risk Brugada syndrome (BrS) with recurrent ventricular fibrillation (VF) are limited. Catheter ablation is increasingly performed but a large study with long-term outcome data is lacking. We report the results of the multicenter, international BRAVO (Brugada Ablation of VF Substrate Ongoing Registry) for treatment of high-risk symptomatic BrS. Methods: We enrolled 159 patients (median age 42 years; 156 male) with BrS and spontaneous VF in BRAVO; 43 (27%) of them had BrS and early repolarization pattern. All but 5 had an implantable cardioverter-defibrillator for cardiac arrest (n=125) or syncope (n=34). A total of 140 (88%) had experienced numerous implantable cardioverter-defibrillator shocks for spontaneous VF before ablation. All patients underwent a percutaneous epicardial substrate ablation with electroanatomical mapping except for 8 who underwent open-thoracotomy ablation. Results: In all patients, VF/BrS substrates were recorded in the epicardial surface of the right ventricular outflow tract; 45 (29%) patients also had an arrhythmic substrate in the inferior right ventricular epicardium and 3 in the posterior left ventricular epicardium. After a single ablation procedure, 128 of 159 (81%) patients remained free of VF recurrence; this number increased to 153 (96%) after a repeated procedure (mean 1.2±0.5 procedures; median=1), with a mean follow-up period of 48±29 months from the last ablation. VF burden and frequency of shocks decreased significantly from 1.1±2.1 per month before ablation to 0.003±0.14 per month after the last ablation ( P P =0.0274). There were no arrhythmic or cardiac deaths. Complications included hemopericardium in 4 (2.5%) patients. Conclusions: Ablation treatment is safe and highly effective in preventing VF recurrence in high-risk BrS. Prospective studies are needed to determine whether it can be an alternative treatment to implantable cardioverter-defibrillator implantation for selected patients with BrS. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04420078.

Ultra-low temperature cryoablation (ULTC) using near-critical nitrogen (−196ºC) has been shown to produce durable, contiguous, transmural lesions in ventricles of animal models. This report summarizes acute experience with ULTC in the first-ever 13 patients with recurrent monomorphic ventricular tachycardias (VTs) of both ischemic cardiomyopathy and nonischemic etiologies enrolled in the CryoCure-VT (Cryoablation for Monomorphic Ventricular Tachycardia; NCT04893317) clinical trial. After an average of 9.6 ± 4.6 endocardial ULTC lesions per patient, no clinical ventricular tachycardias were inducible in 91% of patients. Two procedure-related serious adverse events recorded in 2 patients resolved post-procedurally without clinical sequelae. Further investigation of both acute and chronic outcomes is warranted and ongoing.

Introduction Electrogram (EGM) fractionation is often associated with diseased atrial tissue; however, mechanisms for fractionation occurring above an established threshold of 0.5 mV have never been characterized. We sought to investigate during sinus rhythm (SR) the mechanisms underlying bipolar EGM fractionation with high-density mapping in patients with atrial fibrillation (AF). Methods Forty-five patients undergoing AF ablation (73% paroxysmal, 27% persistent) were mapped at high density (18562 +/- 2551 points) during SR (Rhythmia). Only bipolar EGMs with voltages above 0.5 mV were considered for analysis. When fractionation (> 40 ms and >4 deflections) was detected, we classified the mechanisms as slow conduction, wave-front collision, or a pivot point. The relationship between EGM duration and amplitude, and tissue anisotropy and slow conduction, was then studied using a computational model. Results Of the 45 left atria analyzed, 133 sites of EGM fragmentation were identified with voltages above 0.5 mV. The most frequent mechanism (64%) was slow conduction (velocity 0.45 m/s +/- 0.2) with mean EGM voltage of 1.1 +/- 0.5 mV and duration of 54.9 +/- 9.4 ms. Wavefront collision was the second most frequent (19%), characterized by higher voltage (1.6 +/- 0.9 mV) and shorter duration (51.3 +/- 11.3 ms). Pivot points (9%) were associated with the highest degree of fractionation with 70.7 +/- 6.6 ms and 1.8 +/- 1 mV. In 10 sites (8%) fractionation was unexplained. The EGM duration was significantly different among the 3 mechanisms (p = .0351). Conclusion In patients with a history of AF, EGM fractionation can occur at amplitudes > 0.5 mV when in SR in areas often considered not to be diseased tissue. The main mechanism of EGM fractionation is slow conduction, followed by wavefront collision and pivot sites.

Detailed effects of electrode size on electrograms (EGMs) have not been systematically examined.We aimed to elucidate the effect of electrode size on EGMs and investigate an optimal configuration of electrode size and interelectrode spacing for gap detection and far-field reduction.This study included 8 sheep in which probes with different electrode size and interelectrode spacing were epicardially placed on healthy, fatty, and lesion tissues for measurements. Between 3 electrode sizes (0.1 mm/0.2 mm/0.5 mm) with 3 mm spacing. As indices of capability in gap detection and far-field reduction, in different electrode sizes (0.1 mm/0.2 mm/0.5 mm) and interelectrode spacing (0.1 mm/0.2 mm/0.3 mm/0.5 mm/3 mm) and the optimized electrode size and interelectrode spacing were determined. Compared between PentaRay and the optimal probe determined in study 2.Study 1 demonstrated that unipolar voltage and the duration of EGMs increased as the electrode size increased in any tissue (P.001). Bipolar EGMs had the same tendency in healthy/fat tissues, but not in lesions. Study 2 showed that significantly higher gap to lesion volume ratio and healthy to fat tissue voltage ratio were provided by a smaller electrode (0.2 mm or 0.3 mm electrode) and smaller spacing (0.1 mm spacing), but 0.3 mm electrode/0.1 mm spacing provided a larger bipolar voltage (P.05). Study 3 demonstrated that 0.3 mm electrode/0.1 mm spacing provided less deflection with more discrete EGMs (P .0001) with longer and more reproducible AF cycle length (P .0001) compared to PentaRay.Electrode size affects both unipolar and bipolar EGMs. Catheters with microelectrodes and very small interelectrode spacing may be superior in gap detection and far-field reduction. Importantly, this electrode configuration could dramatically reduce artifactual complex fractionated atrial electrograms and may open a new era for AF mapping.

Aims Little is known about patients with right bundle branch block (RBBB)-ventricular tachycardia (VT) and arrhythmogenic cardiomyopathy (ACM). Our aims were: (i) to describe electrocardiogram (ECG) characteristics of sinus rhythm (SR) and VT; (ii) to correlate SR with RBBB-VT ECGs; and (iii) to compare VT ECGs with electro-anatomic mapping (EAM) data. Methods and results From the European Survey on ACM, 70 patients with spontaneous RBBB-VT were included. Putative left ventricular (LV) sites of origin (SOOs) were estimated with a VT-axis-derived methodology and confirmed by EAM data when available. Overall, 49 (70%) patients met definite Task Force Criteria. Low QRS voltage predominated in lateral leads (n = 37, 55%), but QRS fragmentation was more frequent in inferior leads (n = 15, 23%). T-wave inversion (TWI) was equally frequent in inferior (n = 28, 42%) and lateral (n = 27, 40%) leads. TWI in inferior leads was associated with reduced LV ejection fraction (LVEF; 46 ± 10 vs. 53 ± 8, P = 0.02). Regarding SOOs, the inferior wall harboured 31 (46%) SOOs, followed by the lateral wall (n = 17, 25%), the anterior wall (n = 15, 22%), and the septum (n = 4, 6%). EAM data were available for 16 patients and showed good concordance with the putative SOOs. In all patients with superior-axis RBBB-VT who underwent endo-epicardial VT activation mapping, VT originated from the LV. Conclusions In patients with ACM and RBBB-VT, RBBB-VTs originated mainly from the inferior and lateral LV walls. SR depolarization and repolarization abnormalities were frequent and associated with underlying variants.

Aim To describe clinical characteristics, procedural details, specific challenges, and outcomes in patients with HeartMate3™ (HM3), a left ventricular assist device system with a magnetically levitated pump, undergoing ventricular tachycardia ablation (VTA). Methods and results Data were collected from patients with an HM3 system who underwent VTA in seven tertiary centres. Data included baseline patient characteristics, procedural data, mortality, and arrhythmia-free survival. The study cohort included 19 patients with cardiomyopathy presenting with ventricular tachycardia (VT) (53% with VT storm). Ventricular tachycardias were induced in 89% of patients and a total of 41 VTs were observed. Severe electromagnetic interference was present on the surface electrocardiogram. Hence, VT localization required analysis of intra-cardiac signals or the use of filter in the 40–20 Hz range. The large house pump HM3 design obscured the cannula inflow and therefore multi imaging modalities were necessary to avoid catheter entrapment in the cannula. A total of 32 VTs were mapped and were successfully ablated (31% to the anterior wall, 38% to the septum and only 9% to the inflow cannula region). Non-inducibility of any VT was reached in 11 patients (58%). Over a follow-up of 429 (interquartile range 101–692) days, 5 (26%) patients underwent a redo VT ablation due to recurrent VTA and 2 (11%) patients died. Conclusions Ventricular tachycardia ablation in patients with HM3 is feasible and safe when done in the appropriate setup. Long-term arrhythmia-free survival is acceptable but not well predicted by non-inducibility at the end of the procedure.

INTRODUCTION: Microstructural abnormalities at the epicardium of the right ventricular outflow tract (RVOT) may provide the arrhythmia substrate in Brugada syndrome (BrS). Endocardial unipolar electroanatomical mapping allows the identification of epicardial abnormalities. We evaluated the clinical implications of an abnormal endocardial substrate as perceived by high-density electroanatomical mapping (HDEAM) in patients with BrS. METHODS: Fourteen high-risk BrS patients with aborted sudden cardiac death (SCD) (12 males, mean age: 41.9 ± 11.8 years) underwent combined endocardial-epicardial HDEAM of the right ventricle/RVOT, while 40 asymptomatic patients (33 males, mean age: 42 ± 10.7 years) underwent endocardial HDEAM. Based on combined endocardial-epicardial procedures, endocardial HDEAM was considered abnormal in the presence of low voltage areas (LVAs) more than 1 cm2 with bipolar signals less than 1 mV and unipolar signals less than 5.3 mV. Programmed ventricular stimulation (PVS) was performed in all patients. RESULTS: The endocardial unipolar LVAs were colocalized with epicardial bipolar LVAs (p = .0027). Patients with aborted SCD exhibited significantly wider endocardial unipolar (p

Background Purkinje ectopics (PurkEs) are major triggers of idiopathic ventricular fibrillation (VF). Identifying clinical factors associated with specific PurkE characteristics could yield insights into the mechanisms of Purkinje-mediated arrhythmogenicity. Objective The purpose of this study was to examine the associations of clinical, environmental, and genetic factors with PurkE origin in patients with PurkE-initiated idiopathic VF. Methods Consecutive patients with PurkE-initiated idiopathic VF from 4 arrhythmia referral centers were included. We evaluated demographic characteristics, medical history, clinical circumstances associated with index VF events, and electrophysiological characteristics of PurkEs. An electrophysiology study was performed in most patients to confirm the Purkinje origin. Results Eighty-three patients were included (mean age 38 ± 14 years; 44 [53%] women), of whom 32 had a history of syncope. Forty-four patients had VF at rest. PurkEs originated from the right ventricle (RV) in 41 patients (49%), from the left ventricle (LV) in 36 (44%), and from both ventricles in 6 (7%). Seasonal and circadian distributions of VF episodes were similar according to PurkE origin. The clinical characteristics of patients with RV vs LV PurkE origins were similar, except for sex. RV PurkEs were more frequent in men than in women (76% vs 24%), whereas LV and biventricular PurkEs were more frequent in women (81% vs 19% and 83% vs 17%, respectively) (P Conclusion PurkEs triggering idiopathic VF originate dominantly from the RV in men and from the LV or both ventricles in women, adding to other sex-related arrhythmias such as Brugada syndrome or long QT syndrome. Sex-based factors influencing Purkinje arrhythmogenicity warrant investigation.

Introduction Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death in patients with hypertrophic cardiomyopathy (HCM). The origin of VF and the success of catheter ablation to eliminate recurrent episodes in this population are poorly understood. Methods and results From 2010 to 2014, five patients with HCM (age 21 ± 9 years, three female) underwent invasive electrophysiological studies and ablation at our center after resuscitation from recurrent (9 ± 7) episodes of VF. Ventricular premature beats (VPBs), seen to initiate VF in certain cases, were recorded noninvasively before the ablation procedure. Postprocedural computed tomography (CT) was performed to correlate ablation sites with myocardial hypertrophy in three patients. Outcomes were assessed by clinical follow-up and implantable cardioverter-defibrillator interrogations. VPB triggers were localized invasively to the distal left Purkinje conduction system (left posterior fascicle [2], left anterior fascicle [1], and both fascicles [2]). All targeted VF triggers were successfully eliminated by radiofrequency ablation in the left ventricle. Among patients with postablation CT imaging, 93 ± 12% of ablation sites corresponded to hypertrophied segments. Over 50 ± 38 months, four of five patients were free from primary VF without antiarrhythmic drug therapy. One patient who had 13 episodes of VF before ablation had a single recurrence. Conclusion In our study of patients with HCM and recurrent VF, VF was not initiated from the myocardium but rather from Purkinje arborization. These sources colocalized with the hypertrophic substrate, suggesting electromechanical interaction. Focal ablation at these sites was associated with a marked reduction in VF burden.

Background Several electrocardiographic (ECG) indices have been proposed to predict the origin of premature ventricular complexes (PVCs) with precordial transition in lead V3. However, the accuracy of these algorithms is limited. Objectives We sought to evaluate a new ECG criterion differentiating the origin of outflow tract with precordial transition in lead V3. Methods We included in our study patients exhibiting outflow tract PVCs with precordial transition in lead V3 referred for ablation. We analyzed a novel new ECG criterion, RV1-V3 transition ratio, for distinguishing right from left idiopathic outflow tract PVCs with precordial transition in lead V3. The RV1-V3 transition ratio was defined as (RV1+RV2+RV3) PVC / (RV1+RV2+RV3) SR (sinus rhythm). Results We included 58 patients in our study. The ratio was lower for right ventricular outflow tract origins than left ventricular outflow tract (LVOT) origins (median [interquartile range], 0.6953 [0.4818–1.0724] vs 1.5219 [1.1582–2.4313], P < .001). Receiver operating characteristic analysis revealed an area under the curve of 0.856 for the ratio, and a cut-off value of ≥0.9 predicting LVOT origin with 94% sensitivity and 73% specificity. This ratio was superior to any previously proposed ECG criterion for differentiating right from left outflow tract PVCs. Conclusion The RV1-V3 transition ratio is a simple and accurate novel ECG criterion for distinguishing right from left idiopathic outflow tract PVCs with precordial transition in lead V3.

Introduction: Ultra-high-density mapping for ventricular tachycardia (VT) is increasingly used. However, manual annotation of local abnormal ventricular activities (LAVAs) is challenging in this setting. Therefore, we assessed the accuracy of the automatic annotation of LAVAs with the Lumipoint algorithm of the Rhythmia system (Boston Scientific). Methods and Results: One hundred consecutive patients undergoing catheter ablation of scar-related VT were studied. Areas with LAVAs and ablation sites were manually annotated during the procedure and compared with automatically annotated areas using the Lumipoint features for detecting late potentials (LP), fragmented potentials (FP), and double potentials (DP). The accuracy of each automatic annotation feature was assessed by re-evaluating local potentials within automatically annotated areas. Automatically annotated areas matched with manually annotated areas in 64 cases (64%), identified an area with LAVAs missed during manual annotation in 15 cases (15%), and did not highlight areas identified with manual annotation in 18 cases (18%). Automatic FP annotation accurately detected LAVAs regardless of the cardiac rhythm or scar location; automatic LP annotation accurately detected LAVAs in sinus rhythm, but was affected by the scar location during ventricular pacing; automatic DP annotation was not affected by the mapping rhythm, but its accuracy was suboptimal when the scar was located on the right ventricle or epicardium. Conclusion: The Lumipoint algorithm was as/more accurate than manual annotation in 79% of patients. FP annotation detected LAVAs most accurately regardless of mapping rhythm and scar location. The accuracy of LP and DP annotations varied depending on mapping rhythm or scar location.

Background Localized staining due to venule injury is attributable to ethanol infusion into the vein of Marshall (Et-VOM). Objective The purpose of this study was to investigate adverse outcomes of localized staining during Et-VOM in patients undergoing ablation for atrial fibrillation. Methods Two hundred four patients (age 64 ± 10 years; 153 male) were sorted based on the aspect of localized staining. Staining of atrial myocardium that spread uniformly along the VOM vascular tree following selective VOM venography was considered normal, in contrast to predominantly localized staining that spread concentrically from a focal point due to vascular injury. Outcomes between the 2 groups were compared. Results Localized staining was observed in 27% of patients. No patients developed clinically significant pericardial effusions during Et-VOM; however, 7 patients developed pericardial effusions on the first postprocedural day (3.6% in patients with vs 3.4% in patients without localized staining). No significant difference was found in achievement of acute mitral isthmus (MI) block (96% vs 98%) and size of the endocardial low-voltage area (8.5 ± 4.1 cm2 vs 9.3 ± 5.3 cm2) in patients with and without localized staining, respectively. Long-term follow-up was not impacted by localized staining. Freedom from recurrent atrial tachyarrhythmias (66% vs 76%) and durability of MI block (57% vs 54%) were not significantly different with and without localized staining. There were no cases of rehospitalization for pericarditis, chronic pericardial effusion, or heart failure. Conclusion In our study, localized staining was frequent but was not associated with clinically relevant impact or disadvantages.

Beyond pulmonary vein isolation, the two main additional strategies: Cox-Maze procedure or targeting of electrical signatures (focal bursts, rotational activities, meandering wavelets), remain controversial. High-density mapping of these arrhythmias has demonstrated firstly that a patchy lesion set is highly proarrhythmogenic, favoring macro-re-entry through conduction slowing and providing pivots for localized re-entry. Secondly, discrete anatomical structures such as the Vein or Ligament of Marshall (VOM/LOM) and the coronary sinus (CS) have epicardial muscular bundles that are more frequently involved in re-entry than previously thought. The Marshall Bundle can be ablated at any point along its course from the mid-to-distal coronary sinus to the left atrial appendage. If necessary, the VOM may be directly ablated using ethanol infusion to eliminate PV contributions and produce conduction block across the mistral isthmus. Ethanol ablation of the VOM, supplemented with RF ablation, may be more effective in producing conduction block at the mitral isthmus than repeat RF ablation alone.

Background Beyond pulmonary vein isolation (PVI), the optimal ablation strategy for persistent atrial fibrillation (AF) remains poorly defined. Objective The purpose of this study was to examine a novel comprehensive ablation strategy (Marshall bundle elimination, Pulmonary vein isolation, and Line completion for ANatomical ablation of persistent atrial fibrillation [Marshall-PLAN]) strictly based on anatomical considerations. Methods Left atrial (LA) sites were sequentially targeted as follows: (1) coronary sinus and vein of Marshall (CS-VOM) musculature; (2) PVI; and (3) anatomical isthmuses (mitral, roof, and cavotricuspid isthmus [CTI]). The primary endpoint was 12-month freedom from AF/atrial tachycardia (AT). Results Seventy-five consecutive patients were included (age 61 ± 9 years; 10 women; AF duration 9 ± 11 months; mean LA volume 197 ± 43 mL). VOM ethanol infusion was completed in 69 patients (92%). The full Marshall-PLAN lesion set (VOM, PVI, mitral, roof, and CTI with block) was successfully completed in 68 patients (91%). At 12 months, 54 of 75 patients (72%) were free from AF/AT after a single procedure (no antiarrhythmic drugs) in the overall cohort. In the subset of patients with a complete Marshall-PLAN lesion set (n = 68), the single procedure success rate was 79%. After 1 or 2 procedures, 67 of 75 patients (89%) remained free from AF/AT (no antiarrhythmic drugs). After 1 or 2 procedures, VOM ethanol infusion was complete in 72 of 75 patients (96%). Conclusion A novel ablation strategy that systematically targets anatomical atrial structures (VOM ethanol infusion, PVI, and prespecified linear lesions) is feasible, safe, and associated with a high rate of freedom from arrhythmia recurrence at 12 months in patients with persistent AF.

Recent data of electrophysiological mapping in patients with Brugada syndrome (BrS) suggest that the presence of an abnormal arrhythmogenic substrate in the epicardial right ventricular outflow tract is responsible for ST-segment elevation and ventricular fibrillation (VF). Complete elimination of the epicardial abnormal potentials normalizes Brugada-pattern electrocardiogram and suppresses VF recurrence. We herein report the first case of BrS in which an injection of adenosine unmasked dormant conduction in the epicardial RVOT after the disappearance of the epicardial potentials.

Background Ultralow temperature cyroablation (ULTC) is designed to create focal, linear, and circumferential lesions. The aim of this study was to assess the safety, efficacy, and durability of atrial and ventricular ULTC lesions in preclinical large animal models. Methods and results The ULTC system uses nitrogen near its liquid-vapor critical point to cool 11-cm ablation catheters. The catheter can be shaped to specific anatomies using pre-shaped stylets. ULTC was used in 11 swine and four sheep to create atrial (pulmonary vein isolation and linear ablation) and ventricular lesions. Acute and 90-day success were evaluated by intracardiac mapping and histologic examination. Cryoadherence was observed during all ULTC applications, ensuring catheter stability at target locations. Local electrograms were completely eliminated immediately after the first single-shot ULTC application in 49 of 53 (92.5%) atrial and in 31 of 32 (96.9%) ventricular applications. Lesion depth as measured on histology preparations was 1.96 ± 0.8 mm in atrial and 5.61 ± 2.2 mm in ventricular lesions. In all animals, voltage maps and histology demonstrated transmural and durable lesions without gaps, surrounded by intact collagen fibers without injury to surrounding tissues. Transient coronary spasm could be provoked with endocardial ULTC in the left ventricle in close proximity to a coronary artery. Conclusions ULTC created effective and efficient atrial and ventricular lesions in vivo without procedural complications in two large animal models. ULTC lesions were transmural, contiguous, and durable over 3 months.

Brugada syndrome (BrS) is a sudden cardiac death syndrome characterized by a coved-type electrocardiogram (ECG). Different disorders, such as ischemia, can emulate a Brugada-pattern ECG (Brugada phenocopy). We report herein, the first case of surgical epicardial electrophysiological mapping in a successfully resuscitated patient with an anomalous aortic origin of the coronary artery (AAOCA) associated with a coved-type ECG. It was debatable whether the coved-type ECG and the abnormal arrhythmogenic substrate in the epicardial right ventricular outflow tract were derived from BrS or from repetitive ischemia due to AAOCA; however, the epicardial electrophysiological mapping helped in deciding the treatment strategy. This article is protected by copyright. All rights reserved.

Substrate-based catheter ablation approaches to ventricular tachycardia (VT) focus on low-voltage areas and abnormal electrograms. However, specific electrogram characteristics in sinus rhythm are not clearly defined and can be subject to variable interpretation. We analyzed the potential ablation target size using automatic abnormal electrogram detection and studied findings during substrate mapping in the VT isthmus area.Electrogram characteristics in 61 patients undergoing scar-related VT ablation using ultrahigh-density 3D-mapping with a 64-electrode mini-basket catheter were analyzed retrospectively. Forty-four complete substrate maps with a mean number of 10319 ± 889 points were acquired. Fractionated potentials detected by automated annotation and manual review were present in 43 ± 21% of the entire low-voltage area (1.0 mV), highly fractionated potentials in 7 ± 8%, late potentials in 13 ± 15%, fractionated late potentials in 7 ± 9% and isolated late potentials in 2 ± 4%, respectively. Highly fractionated potentials (10 ± 1 fractionations) were found in all isthmus areas of identified VT during substrate mapping, while isolated late potentials were distant from the critical isthmus area in 29%.The ablation target area varies enormously in size, depending on the definition of abnormal electrograms. Clear linking of abnormal electrograms with critical VT isthmus areas during substrate mapping remains difficult due to a lack of specificity rather than sensitivity. However, highly fractionated, low-voltage electrograms were found to be present in all critical VT isthmus sites.

Aims An incomplete understanding of the mechanism of atrial tachycardia (AT) is a major determinant of ablation failure. We systematically evaluated the mechanisms of AT using ultra-high-resolution mapping in a large cohort of patients. Methods and results We included 107 consecutive patients (mean age: 65.7 ± 9.2 years, males: 81 patients) with documented endocardial gap-related AT after left atrial ablation for persistent atrial fibrillation (AF). We analysed the mechanism of 134 AT (94 macro-re-entries and 40 localized re-entries) using high-resolution activation mapping in combination with high-density voltage and entrainment mapping. Voltage in the conducting channels may be extremely low, even Conclusion High-resolution activation mapping in combination with high-density voltage and entrainment mapping is the ideal strategy to delineate the critical part of the circuit in endocardial gap-related re-entrant AT after AF ablation.

The risk for life-threatening arrhythmia in patients with surgically corrected congenital heart disease is very low and is most commonly owing to scar in the area of a repaired ventricular septum defect or ischemia.1 We present a rare case of scar-related ventricular tachycardia (VT) in the area of the sinus of Valsalva (SV) late after surgically corrected dextro-transposition of the great arteries (d-TGA). Key teaching points • Patients with repaired d-transposition of the great arteries might experience scar-related ventricular tachycardia originating from the aortic root. • Detailed preinterventional imaging is necessary to identify the scar area. • Preinterventional imaging allows to choose the optimal ablation approach from different anatomical sites.

Aims Risk stratification of sudden cardiac arrest (SCA) in Brugada syndrome (Brs) remains the main challenge for physicians. Several scores have been suggested to improve risk stratification but never replicated. We aim to investigate the accuracy of the Brs risk scores. Methods and results A total of 1613 patients [mean age 45 ± 15 years, 69% male, 323 (20%) symptomatic] were prospectively enrolled from 1993 to 2016 in a multicentric database. All data described in the risk score were double reviewed for the study. Among them, all patients were evaluated with Shanghai score and 461 (29%) with Sieira score. After a mean follow-up of 6.5 ± 4.7 years, an arrhythmic event occurred in 75 (5%) patients including 16 SCA, 11 symptomatic ventricular arrhythmia, and 48 appropriate therapies. Predictive capacity of the Shanghai score (n = 1613) and the Sieira (n = 461) score was, respectively, estimated by an area under the curve of 0.73 (0.67–0.79) and 0.71 (0.61–0.81). Considering Sieira score, the event rate at 10 years was significantly higher with a score of 5 (26.4%) than with a score of 0 (0.9%) or 1 (1.1%) (P Conclusions In the largest cohort of Brs patient ever described, risk scores do not allow stratifying the risk of arrhythmic event in intermediate-risk patient.

Aims The precise localization of manifest posteroseptal accessory pathways (APs) often poses diagnostic challenges considering that a small area may encompass AP that may be ablated from the right or left endocardium, or epicardially within the coronary sinus (CS). We sought to explore whether the QRS transition pattern in the precordial lead may help to discriminate the necessary ablation approach. Methods and results Consecutive patients who underwent a successful ablation of a single manifest AP over a 5-year period were included. Standard 12-lead electrocardiograms were reviewed. A total of 273 patients were identified. Mean age was 31 ± 15 years and 62% were male. Of the 110 identified posteroseptal AP, 64 were ablated from the right endocardium, 33 from the left endocardium, and 13 inside the CS. While a normal precordial QRS transition was most often observed, a subset of 33 patients presented an atypical ‘double transition’ pattern which specifically identified right endocardial AP. The combination of a q wave in V1 with a proportion of the positive QRS component in V1 V3, predicted a right endocardial AP with a 100% specificity. In case of a positive QRS sum in V2, this ‘double transition’ pattern predicted a posteroseptal right endocardial AP with 99.5% specificity and 44% sensitivity. The positive predictive value was 97%. The only false positive was a midseptal AP. In the case of a negative or isoelectric QRS sum in V2, APs were located more laterally on the tricuspid annulus. Conclusion The combination of a q wave in V1 with a double QRS transition pattern in the precordial leads is highly specific of a right endocardial AP and rules out the need for CS or left-sided mapping.

Background Data on the optimal location of the ECG leads for the diagnosis of drug-induced long QT syndrome (diLQTS) with Torsades de Pointes (TdP) are lacking. Methods We systematically reviewed the literature for ECGs of patients with diLQTS and subsequent TdP. We assessed T-wave morphology in each lead and measured the longest QT interval in the limb and chest leads in a standardized fashion. Results Of 84 patients, 61.9% were female and mean age was 58.8 years. QTc was significantly longer in chest versus limb leads (mean (standard deviation) 671 (102) vs 655 (97) ms, p=0.02). Using only limb leads for QT interpretation, 18 (21.4%) ECGs were non-interpretable: 10 (11.9%) due to too flat T-waves, 7 (8.3%) due to frequent, early PVCs and 1 (1.2%) due to too low ECG recording quality. In the chest leads, ECGs were non-interpretable in 9 (10.7%) patients: 6 (7.1%) due to frequent, early PVCs, 1 (1.2%) due to insufficient ECG quality, 2 (2.4%) due to missing chest leads but none due to too flat T-waves. The most common T-wave morphologies in the limb leads were flat (51.0%), broad (14.3%) and late peaking (12.6%) T-waves. Corresponding chest lead morphologies were inverted (35.5%), flat (19.6%) and biphasic (15.2%) T-waves. Conclusions Our results indicate that QT evaluation by limb leads only underestimates the incidence of diLQTS experiencing TdP and favors the screening using both limb and chest lead ECG. This article is protected by copyright. All rights reserved.

Objectives This study systematically evaluated mechanisms of atrial tachycardia (AT) by using ultra-high-resolution mapping in a large cohort of patients. Background An incomplete understanding of the mechanism of AT is a major determinant of ablation failure. Methods Consecutive patients with ≥1 AT (excluding cavotricuspid isthmus–dependent flutter) were included. Mapping was performed with a 64-pole mapping catheter. The AT mechanism was defined based on activation mapping and confirmed by entrainment in selected cases. Results A total of 132 patients were included (60 ± 12 years; 31 [23%] female; 111 [84%] previous atrial fibrillation [AF] ablation; 5 [4%] previous left atriotomy). One hundred four (94%) of the 111 post–AF ablation AT patients had substrate-based ablation during the index AF ablation. A total of 214 ATs were mapped, with complete definition of the AT mechanism in 206 (96%). A total of 129 (60%) had anatomic macro re-entry (circuit diameter 44.2 ± 9.6 mm), 57 (27%) had scar-related localized re-entry (circuit diameter 25.8 ± 12.2 mm), and 20 (9%) had focal AT. Fifty-eight (45%) patients had multiple ATs (27 [20%] dual-loop re-entry; 60 [43%] sequential AT) with complex and highly variable transitions between AT circuits. A total of 116 (90%) of 129 macro re-entrant ATs, 56 (98%) of 57 localized AT, and 20 (100%) of 20 focal ATs terminated after radiofrequency ablation. After a mean follow-up of 13 ± 9 months, 57 (46%) patients experienced recurrence of AT. Conclusions Among patients with AT in the context of previous atrial interventions, particularly post–AF ablation patients, multiple complex AT circuits are common. Despite complete delineation of arrhythmia circuits using ultra-high-resolution mapping and high acute ablation success rates, long-term freedom from AT is modest.

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 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.

Idiopathic ventricular fibrillation is diagnosed in patients who survived a ventricular fibrillation episode without any identifiable structural or electrical cause after extensive investigations. It is a common cause of sudden death in young adults. The study reviews the diagnostic value of systematic investigations and the new insights provided by detailed electrophysiological mapping. Recent studies have shown the high incidence of microstructural cardiomyopathic areas, which act as the substrate of ventricular fibrillation re-entries. These subclinical alterations require high-density endo- and epicardial mapping to be identified using electrogram criteria. Small areas are involved and located individually in various sites (mostly epicardial). Their characteristics suggest a variety of genetic or acquired pathological processes affecting cellular connectivity or tissue structure, such as cardiomyopathies, myocarditis, or fatty infiltration. Purkinje abnormalities manifesting as triggering ectopy or providing a substrate for re-entry represent a second important cause. The documentation of ephemeral Purkinje ectopy requires continuous electrocardiography monitoring for diagnosis. A variety of diseases affecting Purkinje cell function or conduction are potentially at play in their pathogenesis. Comprehensive investigations can therefore allow the great majority of idiopathic ventricular fibrillation to ultimately receive diagnoses of a cardiac disease, likely underlain by a mosaic of pathologies. Precise phenotypic characterization has significant implications for interpretation of genetic variants, the risk assessment, and individual therapy. Future improvements in imaging or electrophysiological methods may hopefully allow the identification of the subjects at risk and the development of primary prevention strategies., Highlights • VF can be unexplained despite extensive investigations, notably in the young. • The use of high-density electrophysiological mapping detects causes in the great majority of victims. • Microstructural cardiomyopathies are the main causes, likely underlain by multiple pathological processes. • The phenotypic characterization of substrate is critical to develop therapy and interpret genetic results., Central Illustration

Background No study to date has used high-density mapping to investigate the relationship between prior radiofrequency (RF) lesions for persistent atrial fibrillation (PsAF) ablation and subsequent atrial tachycardias (ATs). Methods From 41 consecutive patients who underwent AT ablation at a second procedure using an ultrahigh-density mapping system, 22 patients (38 ATs) were included as they also had complete maps with a multipolar catheter and three-dimensional (3D) mapping system at the time of the first PsAF ablation procedure. We, therefore, compared voltage maps from the first AF ablation procedure to those from the subsequent AT ablation procedure, as well as the lesion sets used for AF ablation vs the activation patterns in AT during the second procedure. Results In the 38 ATs, 211 of 285 analyzed atrial areas displayed low voltage area (LVA) (74%). Eighteen percent (38/211) existed before the index ablation for AF while 82% (173/211) were newly identified as LVA during the second procedure. Ninety-nine percent (172/173) of the newly developed LVA colocalized with RF lesions delivered for PsAF. Of the 38 ATs, 89.5% (34/38) AT circuits were associated with newly developed LVA due to RF lesions whilst 10.5% (4/38) AT circuits were associated with pre-existing LVA observed at the index procedure. No AT circuit was completely independent from index RF lesions in this series. Conclusions Analysis of detailed 3D electroanatomical mapping demonstrates that most ATs after PsAF ablation are involving LVAs due to index RF lesions.

Despite a strong genetic background, Brugada syndrome (BrS) mainly affects middle-age patients. Data are scarce in the youngest and oldest age groups.The purpose of this study was to describe the clinical characteristics and variations in rhythmic risk in BrS patients according to age.Consecutive BrS patients diagnosed in 15 French tertiary centers in France were enrolled from 1993 to 2016 and followed up prospectively. All of the clinical and ECG data were double reviewed.Among the 1613 patients enrolled (age 45 ± 15 years; 69% male), 3 groups were defined according to age (52 patients17 years; 1285 between 17 and 59 years; and 27660 years). In the youngest patients, we identified more female gender (42%), diagnosis by familial screening (63%), previous sudden cardiac death (15%), SCN5A mutation (62%) sinus dysfunction (8%) and aVR sign (37%) (P.001). The oldest patients had the same clinical characteristics except for gender (40% women; P.001). During median follow-up of 5.5 [2.1, 10.0] years, 91 patients experienced an arrhythmic event, including 7 (13%) in the youngest patients, 80 (6%) in middle-age patients, and 4 (1%) in the oldest patients. Annual event rates were 2.1%, 1%, and 0.3%, respectively (P.01).Age on diagnosis changes the clinical presentation of BrS. Although children are identified more during familial screening, they present the highest risk of sudden cardiac death, which is an argument for early and extensive familial screening. The oldest patients present the lowest risk of SCD.

BACKGROUND Use of lesion metric indices is a proposed strategy to support pulmonary vein isolation procedures and these indices show good correlations with lesion sizes. The aim of this in silico study is to provide a detailed analysis of radiofrequency (RF) settings, including high-power short-duration (HPSD) settings, and resulting lesion metric indices. METHODS AND RESULTS A software program was designed which simulated virtual RF ablations. Lesion metric indices (Ablation index: AI, Lesion size index: LSI) were calculated based on underlying RF settings (contact force [CF], power, duration). In series of calculations, the applied settings were varied within defined ranges (CF: 1-80 g, power: 1-60 W, duration: 1-60 seconds). Overall, n = 388 000 virtual ablations were calculated. The resulting lesion metric indices were compared with each other and analyzed in relation to respective RF settings. Increasing contact force from 1 to 10 g resulted in a 4.4-fold LSI value, whilst increasing contact force from 10 to 20g resulted in a 1.5-fold value (P

Introduction Cardioneuroablation (CNA) is a technique used to modulate cardiac parasympathetic tone in patients with sino-atrial (SA) and atrio-ventricular (AV) vagally mediated syncope. We describe the case of a patient who developed AV block after a first procedure of CNA, requiring a second procedure. Case presentation A 47-Year-old man presented with recurrent syncope (daily episodes) associated with high vagal tone conditions. An ECG monitoring showed frequent episodes of sinus bradycardia and sinus arrest, with pauses up to 17 seconds. AV node conduction impairment was never identified. A CNA procedure targeting the right superior and posterior ganglionated plexi (GPs), both from the left and right atrium, was performed with acute success. The subsequent night, repetitive episodes of AV block with normal sinus rate were observed. A second procedure was performed targeting the posteromedial left GP. Follow-up at 4 months showed no recurrent syncopal event and no bradyarrhythmia episode on the implantable loop recorder. Conclusion This case report demonstrates that ablation limited to the right superior and posterior GPs may not be enough for neurocardiogenic syncope and a more systematic approach, extending the ablation to the posteromedial left GP, should be considered.