Sustained ventricular tachycardia and ventricular fibrillation (VF) are life-threatening arrhythmias which remain highly prevalent in patients with advanced heart failure. These ventricular arrhythmias may impair the support provided by CF-LVADs and lead to frequent hospitalizations, antiarrhythmic medication use, external defibrillations, and need for heart transplantation. We report a case in which a patient with a CF-LVAD and an ICD at end-of-life (EOL) presented with asymptomatic low-flow alarms and was found to have VF of unknown duration. Unique in our case was the presence of organized contractility and rhythmic opening of the mitral valve on echocardiogram despite VF on ECG.

Background: Ablation index (AI) linearly correlates with lesion depth and may yield better therapeutic performance in pulmonary vein isolation (PVI) when tailored to a patient’s wall thickness (WT) in the left atrium (LA). Methods and results: (First study) In paroxysmal atrial fibrillation patients (PAF, n=20), the average LA WT (mm) in each anatomical segment for PVI was measured by intra-cardiac echocardiography (ICE) placed in the LA; the optimal AI for creating one-millimeter transmural lesion (AI/mm) was calculated. (Second study) PAF (n=80) patients were randomly assigned either to a force-time integral protocol (FTI, 400 gram·second, n=40) or a tailored-AI protocol (TAI, n=40). In TAI, the LA WT in each segment was individually measured by ICE before starting ablation; a target AI was adjusted according to the individual WT in each segment (AI/mm×WT). The acute procedure outcomes and the 1-year AF recurrence rate were compared between FTI and TAI. TAI had higher success rate of first-pass isolation and had lower incidence of residual PV-potentials/conduction gaps after a circular ablation than FTI (88% vs. 65%, 15 vs. 45%, respectively). The procedure time to complete PVI decreased in TAI compared to FTI (52 vs. 83 minutes), being attributed to the increased radiofrequency power and the decreased radiofrequency application time in each point in TAI. TAI had lower 1-year AF recurrence rate than FTI. Conclusion: WT-based AI-adjustment increased acute procedure success, decreased time for PVI, and reduced 1-year AF recurrence rate. Understanding the precise ablation target would improve the efficacy of PVI.

Arrhythmia Induced Cardiomyopathy: What are Predictors of Myocardial Recovery?Acile Nahlawi BS, Marwan M. Refaat MDDepartment of Internal Medicine, Division of Cardiology, American University of Beirut Medical Center, Beirut, LebanonRunning Title: AIC and Predictors of Myocardial RecoveryDisclosures: NoneFunding: NoneKeywords: Cardiac Arrhythmias, Cardiovascular Diseases, Heart Diseases, Congestive Heart Failure, CardiomyopathyWords: 958 (excluding references)Correspondence:Marwan M. Refaat, MD, FACC, FAHA, FHRS, FASE, FESC, FACP, FRCPAssociate Professor of MedicineDirector, Cardiovascular Fellowship ProgramDepartment of Internal Medicine, Cardiovascular Medicine/Cardiac ElectrophysiologyDepartment of Biochemistry and Molecular GeneticsAmerican University of Beirut Faculty of Medicine and Medical CenterPO Box 11-0236, Riad El-Solh 1107 2020- Beirut, LebanonFax: +961-1-370814Clinic: +961-1-759616 or +961-1-355500 or +961-1-350000/+961-1-374374 Extension 5800Office: +961-1-350000/+961-1-374374 Extension 5353 or Extension 5366 (Direct)Email: [email protected] cause a significant public health burden and improvement in sudden cardiac death risk stratification helped in decreasing mortality by improved pharmacotherapy as well as device implantations including implantable cardiac defibrillators and cardiac resynchronization therapy [1-4]. Arrhythmia induced cardiomyopathy (AIC) is a major cause of non-ischemic cardiomyopathy and heart failure (HF) worldwide [5]. It is characterized by an impairment of left ventricular systolic function secondary to high heart rate (tachycardia-induced), asynchrony (frequent premature ventricular contractions-induced or right ventricular pacing-induced) or an irregular rhythm (such as atrial fibrillation-induced) that serves as the trigger of AIC and this is mediated by calcium mishandling. The distinctive feature of AIC is the substantial improvement in left ventricular systolic function following arrhythmia suppression or elimination [5]. Atrial Fibrillation (AF) is concomitantly present with and potentially the cause of 10 to 50% of HF cases [6]. AIC is an important, commonly encountered and potentially reversible entity that is often under-recognized. The exact incidence and prevalence of AIC remains poorly defined in the literature [7]. In some studies, it was present in as high as 50% of patients with AF undergoing ablation, while it was reported to be present in 10% of patients with focal atrial tachycardia undergoing ablation [8]. In addition, very little attention, if any, is given to AIC in major trials on AF and HF, despite its significant implications on morbidity and mortality and the promising benefits of treatment [7]. Many aspects of AIC are yet to be understood. In fact, few studies limited by small sample size constitute our main source of knowledge on extent and predictors of ventricular recovery after treatment initiation in patients with AIC [9,10].In their multicenter retrospective study, Gopinathannair et al. aimed to assess the degree of recovery of the left ventricular systolic function after suppression/elimination of the underlying arrythmia and to evaluate factors influencing this response such as baseline patient and arrhythmia characteristics. The study sample comprised 243 patients from 3 different institutions whose charts were reviewed retrospectively (no recruitment timeframe was indicated). The patient characteristics studied included baseline left ventricular ejection fraction (LVEF), presence of structural heart disease (SHD) [ defined as significant coronary artery disease, prior myocardial infarction, hemodynamically significant valvular heart disease, or other structural cardiomyopathies] and medications used. As for the arrhythmia characteristics, they included arrhythmia duration and arrhythmia type. The authors used echocardiography as the imaging modality to determine extent of ventricular function recovery by comparing myocardial function before and after treatment of the culprit arrhythmia. The echocardiographic parameters that were assessed included LVEF, LV end-diastolic and end-systolic diameters, left atrial dimension, valvular abnormalities, right ventricular systolic pressures, and pulmonary arterial pressures.In contrast to reported literature on the topic, Gopinathannair et al. found that none of the studied patient and arrhythmia characteristics had a significant effect on the recovery of ventricular function. Their results showed that initiation of aggressive arrhythmia treatment is warranted in patients with suspected AIC, regardless of arrhythmia duration, arrhythmia type, severity of baseline LVEF, and underlying structural heart disease. This was concluded based on the consistent substantial improvement in LVEF after arrhythmia suppression/elimination, mainly through rhythm control, across all different subgroups. In fact, the extent of LVEF improvement was similar whether comparing the group with known arrhythmia duration [KN] to that with unknown arrhythmia duration [UKN] (21.2±9 % vs 19.4±11 %, p-value =0.16) or comparing the group with longest arrhythmia duration to the rest (21.5±7.5 % vs 21.0 ± 9.2%, p-value=0.77). On the other hand, greatest improvement was seen in the group with lowest initial LVEF (24±17 vs 19±7%; p-value <0.0001), making low index LVEF the only predictor of LVEF recovery after arrhythmia treatment in patients with AIC. However, the LVEF in these patients did not reach complete normalization; they had lower post-treatment LVEF compared to other groups (45±14 vs 54±8%; p<0.0001), a finding consistent with the available literature. Also similar to previous studies, the authors found that patients with PVCs experienced smaller extent of recovery compared to other arrhythmia types. The authors concluded by stressing the importance of suspecting AIC in patients having cardiomyopathy with a persistent arrhythmia and initiating aggressive arrhythmia treatment regardless of initial patient and arrhythmia characteristics.As for the limitations of the study by Gopinathannair et al., there are few to mention. First, the study had a retrospective design and therefore findings only serve to generate hypotheses that need further testing and validation. Second, there is a lack of a control group to exclude interference of confounding factors. Although the use of Angiotensin-Converting Enzyme inhibitors (ACEi)/ Angiotension receptor blockers (ARB) did not independently predict LVEF improvement in multivariate analysis, it could still be a confounder given the lower rates of ACEi/ARB use in the cohort. Third, the timeframe of the study and the period of follow-up were not clearly defined. Fourth, there is lack of blinding of echocardiographic analyses which can potentially lead to inter- and intra-observer variability. Finally, the sample population was not diverse as it consisted in its majority of Caucasians.The Gopinathannair et al. study demonstrated several points of strength. Among these are its multicenter nature and its relatively larger sample size compared to similar studies, giving its findings more weight. Moreover, the authors appropriately and clearly defined their inclusion and exclusion criteria. Furthermore, no funding was needed for the study which potentially frees it from direct or indirect influences on its design, execution and interpretation. Finally, the study has successfully improved our understanding of predictors of ventricular recovery in patients with AIC and showed that patients with AIC who had the longest duration of arrhythmia still had LV systolic function improvement with arrhythmia suppression/elimination. This study paves the way for prospective studies and randomized clinical trials to validate the generated hypotheses and corroborate the observational findings.

BACKGROUND The success rate after cryoballoon ablation (CB-A) performed for paroxysmal atrial fibrillation (PAF) might be underestimated by traditional noninvasive monitoring techniques. The purpose of this study was to evaluate the mid-term outcome of CB-A in patients with PAF implanted with an implantable loop recorder (ILR) after the procedure. METHODS Between January 2017 and March 2019, all patients who underwent CB-A for PAF and who were subsequently implanted with an ILR were retrospectively included. All devices were equipped with remote monitoring. All ILR-documented atrial tachycardia (AT) or AF episodes ≥ 6 minutes were considered as recurrence; both true and false episodes were collected. A 3-month post-procedural blanking period (BP) was applied. RESULTS A total of 102 patients (77 male, mean age 60.6 ± 9.6 years) who underwent pulmonary vein isolation (PVI) by CB-A were included; mean time from first diagnosis of AF to PVI was 51.5 ± 46.9 months. Mean follow-up was 29.3 ± 8.1 months; at 12-month follow-up, the success rate was 64.7%, while at 2-year follow-up, freedom from AT/AF recurrences was achieved in 44.1% of the patients. In the follow-up, a total of 4987 ECG strips were analyzed; true-positive episodes were confirmed in 2026 cases (40.6%), while 2961 episodes (59.4%) were considered false-positive. CONCLUSION In patients with PAF implanted with an ILR, CB-A results in freedom from any AT/AF recurrence in 64.7% of patients at 12-month follow-up and in 44.1% of patients when evaluated at 2-year. Careful adjudication of all ILR-documented AF episodes is required to avoid misdiagnosis.

Despite being first described over 30 years ago, focal radiofrequency (RF) continues to be the most widely used energy modality for catheter ablation. The fact that it has managed to hold its own against stiff competition from alternative energy sources used for pulmonary vein isolation (PVI) is down to continuous evolution based on enhancements in our understanding of its biophysical principles. In particular, the advent of contact-force (CF) based integrated indices such as Ablation Index have improved both efficacy and safety. However, a significant limitation of this approach is the absence of tissue feedback during lesion creation, which results in a blunt ‘one-size-fits-all’ approach. This limitation has been further brought into focus by the recent appreciation of the much greater importance of circuit impedance rather than delivered power as a fundamental determinant of RF lesion size.

Introduction: Human atria comprise distinct epicardial layers, which can bypass endocardial layers and lead to downstream centrifugal propagation at the “epi-endo” connection. We sought to characterize anatomical substrates, electrophysiological properties, and ablation outcomes of “pseudo-focal” atrial tachycardias (ATs), defined as macroreentrant ATs mimicking focal ATs. Methods and Results: We retrospectively analyzed ATs showing centrifugal propagation with post-pacing intervals (PPIs) after entrainment pacing suggestive of a macroreentry. A total of 26 patients had pseudo-focal ATs consisting of 15 perimitral, 7 roof-dependent, and 5 cavotricuspid isthmus (CTI)-dependent flutters. A low-voltage area was consistently found at the collision site and co-localized with epicardial layers like the: (1) coronary sinus-great cardiac vein bundle (22%); (2) vein of Marshall bundle (15%); (3) Bachmann bundle (22%); (4) septopulmonary bundle (15%); (5) fossa ovalis (7%); and (6) low right atrium (19%). The mean missing tachycardia cycle length (TCL) was 67 ± 29 ms (22%) on the endocardial activation map. PPI was 9 [0-15] ms and 10 [0-20] ms longer than TCL at the breakthrough site and the opposite site, respectively. While feasible in 25 pseudo-focal ATs (93%), termination was better achieved by blocking the anatomical isthmus than ablating the breakthrough site [24/26 (92%) vs. 1/6 (17%); p < 0.001]. Conclusion: Perimitral, roof-dependent, and CTI-dependent flutters with centrifugal propagation are favored by a low-voltage area located at well-identified epicardial bundles. Comprehensive entrainment pacing maneuvers are crucial to distinguish pseudo-focal ATs from true focal ATs. Blocking the anatomical isthmus is a better therapeutic option than ablating the breakthrough site.

SCN5A gene variants are associated with both Brugada syndrome and conduction disturbances, sometimes expressing an overlapping phenotype. Functional consequences of SCN5A variants assessed by patch clamp electrophysiology are particularly beneficial for a correct pathogenic classification and are related to disease penetrance and severity. Here, we identify a novel SCN5A loss of function variant, p.1449Y>H, which presented with high penetrance and complete left bundle branch block, totally masking the typical findings on the electrocardiogram. We highlight the possibility of this overlap combination that makes impossible an electrocardiographic diagnosis and, through a functional analysis, associate the p.1449Y>H variant to SCN5A pathogenicity.

Transseptal left atrial catheterization is routinely used for many common catheter-based interventions. Tools for transseptal catheterization have advanced over the recent years. Such tools include imaging advances with intracardiac echocardiology as well as an array of needles, wires, and dilators to achieve transseptal access with greater ease and safety. This review will discuss the contemporary tools for transseptal catheterization and guidance for difficult cases.

Introduction: The extravascular ICD (EV ICD) system with substernal lead placement is a novel non-transvenous alternative to current commercially available ICD systems. The EV ICD provides defibrillation and pacing therapies without the potential long-term complications of endovascular lead placement. Methods: This paper summarizes the development of the EV ICD, including the pre-clinical and clinical evaluations that have contributed to system and procedural refinements to date. Results: Extensive pre-clinical research evaluations and 4 human clinical studies with >140 combined acute and chronic implants have enabled the development and refinement of the EV ICD system, currently in worldwide pivotal study. Conclusion: The EV ICD may represent a clinically valuable solution in protecting patients from sudden cardiac death while avoiding the long-term consequences of transvenous hardware. The EV ICD offers advantages over transvenous and subcutaneous systems by avoiding placement in the heart and vasculature; relative to subcutaneous systems, EV ICD requires less energy for defibrillation, enabling a smaller device, and provides pacing features such as anti-tachycardia and asystole pacing in a single system.

Objective: The implantation depth and membranous septum (MS) length are established as the predictors of new-onset conduction disturbance (CD) after transcatheter aortic valve replacement (TAVR) for tricuspid aortic valve (TAV) stenosis. However, little is known about the predictors with bicuspid aortic valve (BAV). This study investigated the role of MS length and implantation depth in predicting CD following TAVR with a balloon-expandable valve in patients with BAV. Methods and results: This retrospective study analyzed 169 patients who underwent TAVR for BAV with balloon-expandable valve, and TAV cohort was established as a control group using propensity score (PS) matching. The primary endpoint was in-hospital new-onset CD (new-onset left bundle branch block or new permanent pacemaker implantation). New-onset CD developed in 37 patients (21.9%). Multivariate analysis revealed severe LVOT calcification (Odds ratio [OR]: 5.83, 95% confidence interval [CI]: 1.08 – 31.5, p = 0.0407) and implantation depth – MS length (OR: 1.30, 95% CI: 1.12 – 1.51, p = 0.0005) as the predictors of new-onset CD within BAV cohort. The matched comparison between BAV and TAV groups showed similar MS length (3.0 vs 3.2mm, p = 0.5307), but valves were implanted deeper in BAV than TAV group (3.9 vs 3.0mm, p < .0001). New-onset CD was more frequent in patients having BAV (22.3% vs 13.9%, p = 0.0458). Conclusion: The implantation depth - MS length, and severe LVOT calcification predicted new-onset CD following TAVR in BAV with balloon-expandable valve. High implantation technique could be considered to avoid new-onset CD in BAV anatomy.

Introduction: Contact force-sensing catheters are widely used for ablation of cardiac arrhythmias. They allow quantification of catheter-to-tissue contact, which is an important determinant for lesion formation and may reduce the risk of complications. The accuracy of these sensors may vary across the measurement range, catheter-to-tissue angle, and amongst manufacturers and we aim to compare the accuracy and reproducibility of four different force sensing ablation catheters. Methods: A measurement setup containing a heated saline water bath with an integrated force measurement unit was constructed and validated. Subsequently, we investigated four different catheter models, each equipped with a unique measurement technology: Tacticath Quartz (Abbott), AcQBlate Force (Biotronik/Acutus), Stablepoint (Boston Scientific), and Smarttouch SF (Biosense Webster). For each model, the accuracy of three different catheters was measured within the range of 0-60 grams and at contact angles of 0°, 30°, 45°, 60°, and 90°. Results: In total, 6685 measurements were performed using 4x3 catheters (median of 568, IQR 511-606 measurements per catheter). Over the entire measurement-range, the force measured by the catheters deviated from the real force by the following absolute mean values: Tacticath 1.29g ±0.99g, AcQBlate Force 2.87g ±2.37g, Stablepoint 1.38g ±1.29g, and Smarttouch 2.26g ±2.70g. For some models, significant under- and overestimation of >10g were observed at higher forces. Mean absolute errors of all models across the range of 10-40g were <3g. Conclusion: Contact measured by force-sensing catheters is accurate with 1-3g deviation within the range of 10g to 40g. Significant errors can occur at higher forces with potential clinical consequences.

Introduction: The risk of typical atrial flutter (AFL) is increased proportionately to right atrial (RA) size or right atrial scarring that results in reduced conduction velocity. These characteristics result in propagation of a flutter wave by ensuring the macro re-entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics and may provide a novel marker of propensity to develop AFL. Our goal was to investigate right atrial collision time (RACT) as a marker of existing or future typical AFL. Methods: This single centre, prospective study recruited consecutive typical AFL ablation patients that were in sinus rhythm. Controls were consecutive electrophysiology study patients >18 years of age. While pacing the coronary sinus (CS) ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral right atrial wall. This RACT is a measure of conduction velocity and distance from CS to a collision point on the lateral right atrial wall. Results: 98 patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 vs 52.4 ± 16.8 years (<0.001) and more often male (34/41vs 31/57 (0.003)). The AFL group mean RACT (132.6±17.3 ms) was significantly longer than that of controls (99.1±11.6 ms) (p<0.001). A RACT cut-off of 115.5 ms had a sensitivity and specificity of 92.7% and 93.0% respectively for diagnosis of atrial flutter. An ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p<0.01). Conclusion: RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies. The ability to predict AFL would be of significant clinical value to guide anticoagulation and ablation decisions.

Despite extreme and undeniable progress in the concept of implantable cardioverter defibrillator (ICD) therapy over the last 40 years, the endocardial lead is still the weakest link of the system. Many efforts have been taken to improve the construction and consequently the durability of the lead. Not all of them were successful and some of the lead models proved to be technically imperfect, resulting in formal recalls. Similarly, patient- and procedure-related factors may strongly affect the lead reliability. The implantation of cardiac electronic devices (CIED) is considered to be a quite common vascular intervention. Also, there are strongly established opinions of best procedural manners, including the most optimal methods of vascular access during the CIED implantations.In this issue of the Journal of Cardiovascular Electrophysiology, Barbhaiya et al. present an interesting retrospective analysis of 660 patients who underwent the ICD implantations in one center from 2011-2017. The goal of the study was to determine the risk factors for premature lead failure. Four implanted leads models were assessed: Biotronik Linox, Sprint Quattro, Durata and Endotak.The main findings include:The ICD lead implantation via cephalic access in multi-lead ICD systems may be a risk factor for premature ICD lead failure (p<0.001).The overall risk of premature ICD lead failure was similar for all the analyzed lead models.Concerns regarding the durability of Biotronik Linox were discussed and the study showed its equal reliability compared to the other leads.Neither age nor gender were the risk factors for premature lead failure.An optimal vascular access for the endocardial lead implantation was investigated in many studies.1-4 So far, cephalic vein cutdown (CVC) was considered to be the method of choice, with the lowest rate of possible complications.2,4,5 Meta-analysis performed by Benz et al. (30 000 patients, more than 50 000 leads) compared CVC and subclavian puncture (SP) and demonstrated lower risk of lead failure when CVC was adopted.2 Axillary vein puncture (AP), especially when ultrasonography-guided, is a feasible technique and significantly reduces the probability of subclavian crush syndrome.6-8 Unfortunately this method is not used by many operators. EHRA survey from 2013 showed that in more than 80% of participating centers, the preferred method for venous access was either CVC or SP.9 What is worth emphasizing, in the study of Barbhaiya et al., axillary access was most often used for lead insertion – 76.8% (61-88%, dependently on the lead model). This fact may potentially explain the main study finding. It is also consistent with the interesting results of the PAIDLESS study presented in the paper of Shaikh et al.3 They showed that experienced operators preferably choose subclavian and/or axillary access (62% of implants), whereas low-volume implanters generally use cephalic vein approach (63%). High-volume operators are also less likely to experience lead failure.An important issue to discuss is the number of leads inserted via cephalic vein. The routine practice, also applied by Barbhaiya and colleagues, includes the placing of atrial and right ventricular leads via cephalic access, if possible. Inserting one or two leads is usually not a problem. There are many inventive ways for doing this, described in literature. Some operators go even further – they use cephalic vein to implant all three leads of cardiac resynchronization therapy (CRT) systems with the success rate of 87.7% - 91.7%.10,11The question of long-term reliability of the leads implanted in such a way is still open. They are tightly packed in one small vessel and possible lead - lead interaction may contribute to their failure. Especially the ICD leads, by definition more complex and sensitive, are prone to damage in these circumstances.Another possible locus minoris resistentiae is the site of cephalic vein ligation after the lead insertion. The line between an adequate and too strong suture tightening is quite narrow. The effort to stop the bleeding from the vein may cause ligation-induced lead insulation damage. Recently, Kajiyama et al. proposed a novel technique for the ligation of the cephalic vein during a two-in-one insertion of the leads.12 It reduces hemorrhaging without decreasing the lead safety.The discussion about the benefits of different vascular access should include the potential disadvantages of future lead extraction, especially in the multi-lead systems. Inserting more than one lead via cephalic vein may determine more problematic transvenous lead extraction procedure (TLE). It may also necessitate the extraction of the functioning lead because of its periprocedural damage during the TLE of the initially targeted lead.The reliability of ICD leads is certainly the most important feature. During the last decades several lead models produced by different manufacturers were recalled because of their serious technical defects. Numerous concerns and divergent literature data regarding the durability of the Linox lead were the premise for the authors to conduct the discussed study. An important observation is that all analyzed lead models, including Linox, were similar in terms of performance (p=0.769).Young and physically active patients were traditionally believed to have a higher risk of lead damage because of the intensive mechanical interaction between the lead and anatomical structures of costoclavicular space. This observation was not confirmed by the authors of the commented paper.The study has several limitations and they are all listed by the authors. The lack of multivariate risk factors analysis is the most important drawback. It could not be performed due to the low overall event rate. All interesting study findings require validation and further investigation.As the ICD lead failure is still a serious problem, the study investigating possible risk factors is always of great importance. With all the limitations, the paper presented by Barbhaiya et al. may be an important guide in dealing with the vascular access during CIED implantations. It sheds new light on the dogma of superiority of cephalic access. What is particularly important in the study outcome and what I personally find a very strong recommendation – is the conclusion that the multiple lead systems should be avoided, if not indicated, especially when combined with cephalic venous access. One possible solution is to use cephalic vein for one lead only. Prospective randomized studies directly comparing axillary and cephalic access would be highly desirable in order to come closer to the idea of the best vascular approach for the endocardial lead implantation.1. Knight BP, Curlett K, Oral H, Pelosi F, Morady F, Strickberger SA. Clinical predictors of successful cephalic vein access for implantation of endocardial leads. J Interv Card Electrophysiol.2002;7(2):177-180.2. Benz AP, Vamos M, Erath JW, Hohnloser SH. Cephalic vs. subclavian lead implantation in cardiac implantable electronic devices: a systematic review and meta-analysis. Europace.2019;21(1):121-129.3. Shaikh ZA, Chung JA, Kersten DJ, et al. Differences in Approaches and Outcomes of Defibrillator Lead Implants Between High-Volume and Low-Volume Operators: Results From the Pacemaker and Implantable Defibrillator Leads Survival Study (”PAIDLESS”). J Invasive Cardiol. 2017;29(12):E184-E189.4. Chan NY, Kwong NP, Cheong AP. Venous access and long-term pacemaker lead failure: comparing contrast-guided axillary vein puncture with subclavian puncture and cephalic cutdown. Europace.2017;19(7):1193-1197.5. Gallik DM, Ben-Zur UM, Gross JN, Furman S. Lead fracture in cephalic versus subclavian approach with transvenous implantable cardioverter defibrillator systems. Pacing Clin Electrophysiol.1996;19(7):1089-1094.6. Belott P. How to access the axillary vein. Heart Rhythm.2006;3(3):366-369.7. Liccardo M, Nocerino P, Gaia S, Ciardiello C. Efficacy of ultrasound-guided axillary/subclavian venous approaches for pacemaker and defibrillator lead implantation: a randomized study. J Interv Card Electrophysiol. 2018;51(2):153-160.8. Squara F, Tomi J, Scarlatti D, Theodore G, Moceri P, Ferrari E. Self-taught axillary vein access without venography for pacemaker implantation: prospective randomized comparison with the cephalic vein access. Europace. 2017;19(12):2001-2006.9. Bongiorni MG, Proclemer A, Dobreanu D, et al. Preferred tools and techniques for implantation of cardiac electronic devices in Europe: results of the European Heart Rhythm Association survey.Europace. 2013;15(11):1664-1668.10. Vogler J, Geisler A, Gosau N, et al. Triple lead cephalic versus subclavian vein approach in cardiac resynchronization therapy device implantation. Sci Rep. 2018;8(1):17709.11. Hadjis A, Proietti R, Essebag V. Implantation of cardiac resynchronization therapy devices using three leads by cephalic vein dissection approach. Europace. 2017;19(9):1514-1520.12. Kajiyama T, Ueda M, Ishimura M, et al. A novel technique for ligation of the cephalic vein reduces hemorrhaging during a two-in-one insertion of dual cardiac device leads. Indian Pacing Electrophysiol J. 2018;18(4):152-154.

We read with great interest the recent study by Rogers, et al. describing lesion formation with continuous versus intermittent radiofrequency ablation.1 The authors applied 50 (ex-vivo) or 10 (in-vivo) watts with either intermittent (15-seconds x4, 30-seconds x2, or 60-seconds x1) or continuous (1, 2, 3, or 5 minutes) radiofrequency applications and examined lesion size with each strategy. Continuous lesions resulted in significantly larger lesion size with possibly increased risk of steam pops at high power. In the ex-vivo model, they saw rapid lesion formation in the first minute of ablation with substantial drop-off in expansion of lesion size over time especially after 3 minutes (down to 0.35mm/min at 5 minutes), and suggest that there is only minimal incremental benefit of prolonging ablation lesion duration beyond 3 minutes in normal tissue.They have, however, appropriately recognized the limitation of their model which lacks significant fibrosis, limiting the generalizability of their findings to ablation in patients with scar. It is important to recognize that lesion formation in scar-related ventricular tachycardia (VT) is likely to differ dramatically compared to normal myocardial tissue. Barkargan, et al. have shown in an in-vivo porcine model of anterior myocardial infarction that lesion formation in normal versus scar tissue can be substantially different.2Specifically, ablation lesions in scar tissue were histologically quite heterogeneous, and connective tissue tended to be more resistant to thermal injury than normal myocardium.We have seen many cases where after identifying critical VT circuit components with activation and entrainment mapping, VT slowing and termination could only be achieved very late (4-5 minutes) into radiofrequency application, suggesting continued lesion expansion due to delayed effect of conductive heating in scar tissue can persist well beyond 3 minutes. Historical data from Nath, et al. have demonstrated that tissue temperature of >50°C must be reached in order to achieve nonreversible cellular damage.3 In the setting of dense scar, as in patients with healed myocardial infarction or dense basal septal scar in nonischemic cardiomyopathy, dynamics of tissue heating and lesion formation are likely quite different than in normal tissue. Especially in intramural substrates which are “protected” by dense subendocardial (or subepicardial if ablating from the epicardium) scar, ablation with very long (>3 minute) lesions may have a more pronounced effect than in normal tissue. While in our experience, steam pops seem to occur less frequently when ablating in dense scar- even with long, high power lesions, close monitoring of ablation parameters including catheter tip temperature and impedance remain necessary during ablation to assure continued safety to avoid char formation and steam pops.We enthusiastically applaud the authors for their valuable contribution to the literature. While chronic cardiomyopathy models are technically difficult to create and costly to maintain, additional studies examining lesion formation in dense scar would be extremely helpful to delineate optimal ablation strategies in patient with cardiomyopathy and difficult VT substrates. Our clinical experience with late VT termination and prevention of inducibility after 4-5 minute radiofrequency ablation lesions in areas of marked fibrosis would support such additional study.References:1. Rogers AJ, Borne RT, Ho G, Sauer WH, Wang PJ, Narayan SM, Zheng L, Nguyen DT. Continuous Ablation Improves Lesion Maturation Compared with Intermittent Ablation Strategies. J Cardiovasc Electrophysiol 2020.2. Barkagan M, Leshem E, Shapira-Daniels A, Sroubek J, Buxton AE, Saffitz JE, Anter E. Histopathological Characterization of Radiofrequency Ablation in Ventricular Scar Tissue. JACC Clin Electrophysiol 2019;5:920-931.3. Nath S, DiMarco JP, Gallop RG, McRury ID, Haines DE. Effects of dispersive electrode position and surface area on electrical parameters and temperature during radiofrequency catheter ablation. Am J Cardiol 1996;77:765-767.

Background: Atrial conduction velocity may represent atrial fibrillation (AF) substrate after pulmonary vein isolation (PVI). To elucidate the association between whole left atrial conduction velocity (LACV) and AF recurrence after PVI. Methods and Results: This observational study enrolled 279 patients who underwent PVI alone as an initial AF ablation procedure. After PVI, the left atrium was mapped with a 20-pole multielectrode in conjunction with the CARTO3 system during 100-ppm right atrial pacing. Left atrial conduction distance and conduction time were calculated from the start to the end of the propagation wave front in the left atrium. LACVs on the anterior and posterior routes were calculated as conduction distance divided by conduction time. Anterior and posterior LACVs were slower in patients with AF recurrence than in those without (anterior, 0.79 [0.71, 0.86] vs. 0.96 [0.90, 1.06], p < 0.001; posterior, 0.99 [0.89, 1.14] vs. 1.10 [1.00, 1.29], p < 0.001). AF recurrence was best predicted by anterior LACV with a cut-off value of 0.87 m/s (sensitivity 87%, specificity 81%, and predictive accuracy 84%). Multivariate analysis demonstrated that a slow anterior LACV < 0.87 m/s was an independent predictor of AF recurrence with an adjusted hazard ratio of 11.8 (6.36 – 22.0). Patients with anterior low-voltage areas demonstrated slower anterior LACV than those without low-voltage areas (0.89 [0.71, 1.00] vs. 0.94 [0.87, 1.05], p < 0.001). Conclusion: A slow LACV in the entire left atrium was an excellent predictor of AF recurrence after PVI, suggesting the necessity of additional ablations.

Catheter ablation is the current standard of care for the management of symptomatic atrial fibrillation (AFib) refractory to pharmacological therapy. One of the complications of this procedure is thermal injury to the esophagus due to its anatomical proximity to the posterior wall of the left atrium (1). Rarely (<1%), an atrioesophageal fistula can form connecting the lumen of damaged esophagus to the atrial chamber (2). This complication is almost always fatal and can result in exsanguination, air embolism, and sepsis (3, 4). With a growing number of catheter ablations being performed each year, the rate of atrioesophageal fistulas is only expected to rise (5). Other more frequent complications include esophageal wall erosions and ulcers (47%), and thermal injury to the vagus nerve plexus leading to esophageal dysmotility and gastroparesis (17%) (6, 7). Therefore, protecting the esophagus from thermal injuries is paramount in ablative procedures and several strategies have been devised to help mitigate this risk. Many physicians monitor the luminal esophageal temperature (LET) [ as a surrogate for intramural esophageal tissue temperature] with a single sensor or multisensor temperature probe and interrupt energy delivery when LET reaches 38°C or 39°C during radiofrequency ablation. However, this technique significantly impacts the procedural workflow due to the waiting periods for LET to return to baseline. Alternative strategies involve cooling of the esophagus with ice water or reducing the ablation lesion power, contact force and/or duration but this strategy may increase the chances for pulmonary vein reconnection (8). To that end, there has been a growing interest in mechanical devices capable of deflecting the esophagus away from the atrium protecting it from thermal injury.In the current issue of the Journal of Cardiovascular Electrophysiology, Houmsse et al. introduce a novel device capable of mobilizing the esophagus laterally to protect it from injury when performing catheter ablation for AFib. Although other devices have been developed and/or used for this purpose (such as the transesophageal echocardiography probe, endotracheal stylet, Esosure stylet and DV8 shaped balloon retractor), this is the only one to operate using vacuum suction allowing it to latch onto the esophageal wall. The device consists of four main components: outer extrusion, inner stacking plates, deflecting arm and control handle. The outer extrusion is inserted via a trochanter or a bougie into the esophagus and is the only portion of the retractor that comes in contact with the surrounding tissues. Small perforations at the distal end allow for vacuum suction to adhere to the esophagus and for a radiocontrast agent to be delivered to delineate the esophageal contour. The inner stacking plates are then introduced through the outer extrusion and are designed to allow movement of the deflecting arm in the medio-lateral plane only. The deflecting arm is connected to the distal end of the stacking plates through a pivot point and can be steered using the control handle. The authors have evaluated the effectiveness and safety of the device on canine and swine animal models by measuring the distance and direction of displacement of the esophagus, examining the cellular architecture after prolonged suction, measuring the LET, and assessing compatibility of device with electroanatomical mapping systems. A total of 68 deviations were performed on four canine models. The average rightward deflection was equal to 26.6 ± 2.5mm compared to 18.7 ± 2.3mm for the direct leftward deflection (p<0.001), and 96% of deviations did not have an esophageal trailing edge. With the exception of one study, the average distance displaced using the suction retractor was superior to other devices (9-13). The substantial distance of deflection and the minimal esophageal trailing edge significantly decreased the rise in LET from baseline (mean increase of 0.2°C vs 2.5°C without deflection). Examination of the esophageal tissue integrity following one hour of continuous suctioning revealed no change in the esophageal cellular architecture, and only minimal circular areas of hyperemia in mucosa due to the suction ports without injury to the muscularis layer. Finally, the retractor did not interfere with the electroanatomical mapping systems used (CARTO and EnSite).Despite its interesting findings, this study has several limitations that should be acknowledged. First, the study was performed on swine and canine animal models, which are known to have an anatomy close to humans; however, the safety profile of the device and its effectiveness in displacing the esophagus may not translate in humans. Second, subjects may exhibit symptoms secondary to extreme deviation of the esophagus in the absence of distortion of the cellular architecture. Clinical studies are needed to assess the safety profile and side effects of this esophageal retractor. Third, it is unclear whether these results would be reproducible under monitored anesthesia care. Finally, the fluoroscopic equipment tools lacked electronic caliper capabilities, and the measurements were performed using radiopaque rulers.Overall, the authors should be commended on their efforts to introduce and evaluate an inexpensive and innovative tool for esophageal protection during AFib ablation. This retractor addresses the limitations of other products that serve a similar purpose. In fact, the suctioning power of the product minimizes the trailing edge of the esophagus that could not be managed with other devices which left esophageal tissue in the ablation field (10, 13). In addition, the control handle offers significant flexibility in device manipulation allowing physicians to choose the site of angulation and the angle of deflection depending on the patient’s anatomy. Future studies should focus on evaluating the safety and effectiveness of this device in humans. Given the growing number of esophageal retracting devices, studies should also aim to determine the device that produces the best esophageal protection and most desirable outcomes of ablation.REFERENCES1. Chung MK, Refaat M, Shen WK, Kutyifa V, Cha YM, Di Biase L, Baranchuk A, Lampert R, Natale A, Fisher J, Lakkireddy DR. Atrial Fibrillation: JACC Council Perspectives. J Am Coll Cardiol. Apr 2020; 75 (14): 1689-1713.2. D’Avila A, Ptaszek LM, Yu PB, Walker JD, Wright C, Noseworthy PA, Myers A, Refaat M, Ruskin JN. Left Atrial-Esophageal Fistula After Pulmonary Vein Isolation. Circulation May 2007; 115(17): e432-3.3. Aryana A, Arthur A, O’ Neill PG, D’Avila A. Catastrophic manifestations of air embolism in a patient with atrioesophageal fistula following minimally invasive surgical ablation of atrial fibrillation. Journal of cardiovascular electrophysiology. 2013;24(8):933-4.4. Stöckigt F, Schrickel JW, Andrié R, Lickfett L. Atrioesophageal fistula after cryoballoon pulmonary vein isolation. Journal of cardiovascular electrophysiology. 2012;23(11):1254-7.5. Oral H, Siontis KC. Prevention of Atrioesophageal Fistula After Catheter Ablation: If the Esophagus Cannot Stand the Heat (Cold), Can It Be Moved to the Sidelines? : JACC: Clinical Electrophysiology; 2017.6. Shah D, Dumonceau J-M, Burri H, Sunthorn H, Schroft A, Gentil-Baron P, et al. Acute pyloric spasm and gastric hypomotility: an extracardiac adverse effect of percutaneous radiofrequency ablation for atrial fibrillation. Journal of the American College of Cardiology. 2005;46(2):327-30.7. Schmidt M, Nölker G, Marschang H, Gutleben K-J, Schibgilla V, Rittger H, et al. Incidence of oesophageal wall injury post-pulmonary vein antrum isolation for treatment of patients with atrial fibrillation. Europace. 2008;10(2):205-9.8. Tran VN, Kusa S, Smietana J, Tsai W-C, Bhasin K, Teh A, et al. The relationship between oesophageal heating during left atrial posterior wall ablation and the durability of pulmonary vein isolation. Ep Europace. 2017;19(10):1664-9.9. Mateos JCP, Mateos EIP, Peña TGS, Lobo TJ, Mateos JCP, Vargas RNA, et al. Simplified method for esophagus protection during radiofrequency catheter ablation of atrial fibrillation-prospective study of 704 cases. Brazilian Journal of Cardiovascular Surgery. 2015;30(2):139-47.10. Bhardwaj R, Naniwadekar A, Whang W, Mittnacht AJ, Palaniswamy C, Koruth JS, et al. Esophageal Deviation During Atrial Fibrillation Ablation: Clinical Experience With a Dedicated Esophageal Balloon Retractor. JACC Clin Electrophysiol. 2018;4(8):1020-30.11. Herweg B, Johnson N, Postler G, Curtis AB, Barold SS, Ilercil A. Mechanical esophageal deflection during ablation of atrial fibrillation. Pacing and clinical electrophysiology. 2006;29(9):957-61.12. Palaniswamy C, Koruth JS, Mittnacht AJ, Miller MA, Choudry S, Bhardwaj R, et al. The extent of mechanical esophageal deviation to avoid esophageal heating during catheter ablation of atrial fibrillation. JACC: Clinical Electrophysiology. 2017;3(10):1146-54.13. Parikh V, Swarup V, Hantla J, Vuddanda V, Dar T, Yarlagadda B, et al. Feasibility, safety, and efficacy of a novel preshaped nitinol esophageal deviator to successfully deflect the esophagus and ablate left atrium without esophageal temperature rise during atrial fibrillation ablation: The DEFLECT GUT study. Heart Rhythm. 2018;15(9):1321-7.

Near-field Signals Detected by a Standard Bipolar Electrode without Detection of Corresponding Signals by Microelectrode: What is the Mechanism?Short title ; Near-filed Microelectrode signalTakashi Nakashima, MD*, Cyril Goujeau, MD, Yosuke Nakatani, MD,Ghassen Cheniti, MD, Pierre Jaïs, MD, Frédéric Sacher, MDAll authors have no conflicts of interest to disclose.Department of Cardiac Electrophysiology, Service de Rhythmologie, Hôpital Cardiologique du Haut-Lévêque (Centre Hospitalier Universtaire de Bordeaux)Avenue de Magellan, 33604, Bordeaux-Pessac, FranceCorrespondence to Takashi Nakashima, MDDepartment of Cardiac Electrophysiology, Service de Rhythmologie, Hôpital Cardiologique du Haut-Lévêque (Centre Hospitalier Universtaire de Bordeaux)Avenue de Magellan, 33604, Bordeaux-Pessac, FranceTel: +33 5 57 65 68 63 19, Fax: +33 5 57 65 68 96 20, Email; [email protected], ORCID: 0000-0002-8538-9259Key words: Ablation; Electrogram analysis; Microelectrode; Ventricular tachycardia

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