A document by David Sanders . Click on the document to view its contents.

Background: The changes in ventricular repolarization after cardiac resynchronization therapy (CRT) are poorly understood. Objective: Address this knowledge gap using a multimodality approach including electrocardiographic and echocardiographic measurements in patients and using patient-specific computational modeling. Methods: In 33 patients electrocardiographic and echocardiographic measurements were performed before and at various intervals after CRT, both during CRT-ON and temporary CRT-OFF. T-wave area was calculated from vectorcardiograms, reconstructed from the 12-lead ECG. Computer simulations were performed using a patient-specific eikonal model of cardiac activation with spatially varying action potential duration (APD) and repolarization rate, fit to a patient’s ECG. Results: During CRT-ON T-wave area diminished within a day and remained stable thereafter, whereas QT-interval did not change significantly. During CRT-OFF T-wave area doubled within 5 days of CRT, while QT-interval and peak-to-end T-wave interval hardly changed. Left ventricular (LV) ejection fraction did not significantly increase before 1 month of CRT. Computer simulations indicated that the increase in T-wave area during CRT-OFF can be explained by changes in APD following chronic CRT that are opposite to the change in CRT-induced activation time. These APD changes were associated with a reduction in LV dispersion in repolarization during chronic CRT. Conclusions: T-wave area during CRT-OFF is a sensitive marker for adaptations in ventricular repolarization during chronic CRT that may include a reduction in LV dispersion of repolarization.

Introduction: Novel ablation catheters equipped with mini-electrodes (ME) offer high resolution mapping for target tissue. This study aimed to evaluate the mapping performance and efficacy of ME catheters in radiofrequency ablation of paroxysmal supraventricular tachycardias (PSVTs). Methods: We prospectively enrolled 136 patients who were undergoing catheter ablation of PSVT including 76 patients with atrioventricular nodal reentrant tachycardia (AVNRT) and 60 patients with atrioventricular reentrant tachycardia (AVRT) or Wolff-Parkinson-White (WPW) syndrome. Patients were randomized to the ME group (ablation using a 4.5mm tip ME catheter) or the control group (ablation using a conventional 4mm tip catheter). The number of ablation attempt and cumulative ablation time to ablation endpoints, which was defined as an emergence of junctional rhythm in AVNRT or accessory pathway (AP) block in AVRT/WPW syndrome were compared. Results: During ablation procedures, discrete SP or AP electrograms were found in 27 (39.7%) patients in the ME group and 13 (19.1%) patients in the control group. The primary study outcomes were significantly lower in the ME group (ablation attempt number: 2.0 [1–4] vs. 3.0 [2–7] in the ME and control group, p=0.032; ablation time: 23.5 [5.0–111.5] vs. 64.5 [16.0–185.0] seconds, p=0.013). According to the PSVT diagnosis, ablation time to junctional rhythm was significantly shorter in the ME group in AVNRT. In AVRT/WPW syndrome, both ablation attempt number and ablation time to AP block showed trends favoring the ME group. Conclusion: The novel ME catheter was advantageous for identifying pathway potentials and reducing initial ablation attempt number and time in PSVT ablation. (ClinicalTrials.gov number, NCT04215640)

An 80-year-old man underwent catheter ablation for atrial tachycardia (AT), which developed after catheter ablation for atrial fibrillation. The AT was diagnosed as dual-loop tachycardia, which included peri-mitral and roof-dependent ATs. An ethanol infusion into the vein of Marshall resulted in left phrenic nerve paralysis. During the procedure, the phrenic nerve paralysis was completely relieved.

The thinning of the skin over the pocket is an occasional phenomenon in patients with cardiac implantable electronic devices (CIEDs) most often associated with the technique of implantation of the device. It is likely that the thinning of the skin over the generator is a risk factor for the development of infectious complications in patients with CIED. Analysis of large database of 3706 patients undergoing transvenous lead extraction (TLE) showed higher number of points of PADIT score and more often previous pocket plastic surgery in patients with too shallow pocket. Most likely, diagnosing only a too shallow CIED pocket is often an early symptom of infection.

Arterial bleeding can take a dramatic course with severe bleeding, therefore it requires an immediate diagnosis and treatment. In this case series, we present 2 cases of arterial injury during pacemaker implantation.

Employing New Criteria for Confirmation of Conduction Pacing – Achieving True Left Bundle Branch Pacing May Be Harder Than Meets the EyeJoshua Sink, MD1, Nishant Verma, MD, MPH2Northwestern University, Feinberg School of Medicine, Department of Internal MedicineNorthwestern University, Feinberg School of Medicine, Division of CardiologyCorresponding Author:Nishant Verma, MD, MPH251 East Huron Street, Feinberg 8-503Chicago, IL 60611312-926-2148Nishant.Verma@nm.orgFunding: NoneDisclosures: Dr. Sink has nothing to disclose. Dr. Verma receives speaker honoraria from Medtronic, Biotronik and Baylis Medical and consulting fees from Boston Scientific, Biosense Webster, AltaThera Pharmaceuticals and Knowledge 2 Practice.Word Count: 1200In recent years, conduction system pacing (CSP) has garnered significant attention from the electrophysiology (EP) community. This movement has been driven by the hypothesis that using the natural conduction system activation is desirable and clinically beneficial in patients with advanced conduction disease and ventricular desynchrony. Permanent His-bundle pacing (PHBP) is generally seen as the purest form of conduction system activation. (Figure 1) PHBP was first described over 20 years ago but the idea has attracted substantial investigative effort in recent years. When successfully achieved, His bundle pacing has been associated with reduction in mortality, reduction in heart failure (HF) admissions, and improvement in left ventricular (LV) function compared to right ventricular (RV) pacing.1 Despite this, consistent achievability in real-world practice remains limited due to a variety of factors including narrow anatomic targetability, lead stability, high pacing thresholds, low ventricular sensing, and inability to correct the QRS in bundle branch block.2Thus, while waiting for the next iteration of improved delivery techniques, pacing leads and programming algorithms,, alternative methods of conductive system pacing have emerged, with the potential to surmount the challenges described.Left bundle branch pacing (LBBP) has recently emerged as an alternative method of CSP. The technique was first described by Huang et al. in 2017 and has seen a momentous rise in interest since.3 In 2019, Huang et al. produced a user manual for a successful LBBP procedure, and in it they attempted to develop the first iteration of criteria for the confirmation of LBBP.4 Utilizing these criteria, or close variations of them, a number of studies were published afterwards that demonstrated preliminary safety, feasibility, and efficacy of LBBP.5,6,7 LBBP became an attractive alternative to His bundle pacing because of the lower thresholds, improved lead stability, and higher procedural success rates. When compared against RV pacing in patients requiring a high burden of pacing, LBBP has demonstrated reduced mortality, HF admissions, and need for upgrade to a BiV device.8 In a small, non-randomized patient sample, LBBP showed greater improvement in LV ejection fraction (EF) compared to BiV pacing.9 Most notably, perhaps, is the astonishing rate of lead placement success, with achievement rates reported as high as 98% in sizable studies.6Differences between the two forms of CSP were apparent from the beginning, including in the appropriate QRS morphology after a successful case. Unlike PHBP, LBBP did not reproduce the native QRS and the QRS duration was often greater than at baseline (Figure 2). The arena of LBBP underwent a notable shift in the Fall of 2021 when Wu et al. proposed new criteria to prove LBBP.10 In this study, they presented an exquisite display of fundamental electrophysiologic principles by using mapping catheters positioned on the His and LV septum during LBB lead placement. Through this painstaking work, they clarified the difference between true LBBP and left bundle branch area pacing (LBBAP), which can incorporate both LBBP and left ventricular septal pacing (LVSP). In their proposed framework, without the presence of a His or LV septum mapping catheter, output dependent QRS transition from non-selective (NS-LBBP) to selective-LBBP (S-LBBP) or LVSP is necessary to prove LBBP and had a sensitivity and specificity of 100%.The present study by Shimeno et al, published in the current issue of the Journal of Cardiovascular Electrophysiology , is the first known effort to document achievement rates of LBBP by utilizing the modified criteria proposed by Wu et al.11 The primary finding of the study is that achieving true LBBP with an acceptable pacing threshold is likely harder than previously realized. As expected, there was improvement after a learning curve, but even in the last third of patients enrolled, the achievement rate of LBBP was only 50%. This is dramatically lower than previously reported achievement rates using the original Huang et al. criteria, and it suggests that not all patients in the previously described studies were actually achieving true LBBP. An unknown subset of patients in these studies was likely only achieving LVSP. This is probably due to a prior reliance on indicators such as a paced right bundle branch block (RBBB) pattern, identification of an intrinsic LBB potential, and/or use of V6 R-wave peak time cutoffs (RWPT) without clear output-dependent QRS transition. It is also worth noting that a variety of RWPT cutoffs have been used seemingly arbitrarily as ‘evidence of LBBP’. This presents a major dilemma and highlights the need for a clear set of LBBP criteria to be defined by the collective EP community. Despite these caveats, many of these previous studies did not fully confirm LBBP in their patients, yet the outcomes from these studies were still clinically promising. This raises the obvious question, does obtaining true LBBP matter? Future studies will need to explore the differences in clinical outcomes between true LBBP and LVSP.Secondarily, Shimeno et al. have provided a useful tool in identifying that LBB potential to QRS-onset ≥ 22ms had a specificity of 98% in predicting LBBP.11 This target measure can help future operators ensure proximal enough engagement of the LBB conduction system. Additionally, the group took a close look at validating a RWPT cutoff time for the prediction of LBBP. Unfortunately, a RWPT cutoff of 68 ms (in non-LBBB patients), determined by the ROC curve, was not highly predictive. This runs contrary to previous reports by Wu et al. and Jastrzebski et al., which reported higher predictive value of RWPT cutoffs10,12 Looking at the data surrounding RWPT cutoffs as a collective, it likely should not be used as a primary metric for confirming LBBP due to imperfect sensitivity and specificity, but it may be an alternative if output dependent QRS transition or change in RWPT of ≥10 ms is not observed. Additionally, in the event that capture thresholds are similar between the LBB and the adjacent myocardium, programmed stimulation is an option to try to reveal a QRS transition by exploiting differences in refractory periods.This study also highlighted one of the unique complications of LBBP by demonstrating a high rate of septal perforation. Paradoxically, more perforations were seen with increased experience, likely highlighting that deeper penetration into the septum is often sought as operators become more familiar with the procedure. The long-term clinical implications of this complication are, thus far, unknown.Looking forward, clear guidelines for confirmation of LBBP need to be defined. This is necessary to ensure quality before undertaking multi-center randomized controlled trials to assess LBBP in comparison to current pacing methods. To date, Wu et al. seem to have provided the best framework to achieve this.10 That said, there are concerns given that this has only been validated in 30 patients (and only 9 with LBBB). In an ideal world, these criteria would be validated in a larger population, though the work to accomplish this would be meticulous given the current gold standard of using an LV septal mapping catheter to prove conduction system capture. Shimeno et al. should be congratulated for their effort in putting this framework to practice. In their work, they have demonstrated that achieving true LBBP as defined by Wu et al. may be harder than meets the eye, and this is very important in assessing the practicality of using LBBP as a widespread alternative to other pacing methods.References:Abdelrahman M, Subzposh FA, Beer D, et al. Clinical Outcomes of His Bundle Pacing Compared to Right Ventricular Pacing. J Am Coll Cardiol . 2018;71(20):2319-2330. doi:10.1016/j.jacc.2018.02.048Zanon F, Abdelrahman M, Marcantoni L, et al. Long term performance and safety of His bundle pacing: A multicenter experience. J Cardiovasc Electrophysiol . 2019;30(9):1594-1601. doi:10.1111/jce.14063Huang W, Su L, Wu S, et al. A Novel Pacing Strategy With Low and Stable Output: Pacing the Left Bundle Branch Immediately Beyond the Conduction Block. Can J Cardiol . 2017;33(12):1736.e1-1736.e3. doi:10.1016/j.cjca.2017.09.013Huang W, Chen X, Su L, Wu S, Xia X, Vijayaraman P. A beginner’s guide to permanent left bundle branch pacing. Heart Rhythm . 2019;16(12):1791-1796. doi:10.1016/j.hrthm.2019.06.016Padala SK, Master VM, Terricabras M, et al. Initial Experience, Safety, and Feasibility of Left Bundle Branch Area Pacing: A Multicenter Prospective Study. JACC Clin Electrophysiol . 2020;6(14):1773-1782. doi:10.1016/j.jacep.2020.07.004Su L, Wang S, Wu S, et al. Long-Term Safety and Feasibility of Left Bundle Branch Pacing in a Large Single-Center Study. Circ Arrhythm Electrophysiol . 2021;14(2):e009261. doi:10.1161/CIRCEP.120.009261Huang W, Wu S, Vijayaraman P, et al. Cardiac Resynchronization Therapy in Patients With Nonischemic Cardiomyopathy Using Left Bundle Branch Pacing. JACC Clin Electrophysiol . 2020;6(7):849-858. doi:10.1016/j.jacep.2020.04.011Sharma PS, Patel NR, Ravi V, et al. Clinical outcomes of left bundle branch area pacing compared to right ventricular pacing: Results from the Geisinger-Rush Conduction System Pacing Registry. Heart Rhythm . 2022;19(1):3-11. doi:10.1016/j.hrthm.2021.08.033Wu S, Su L, Vijayaraman P, et al. Left Bundle Branch Pacing for Cardiac Resynchronization Therapy: Nonrandomized On-Treatment Comparison With His Bundle Pacing and Biventricular Pacing. Can J Cardiol . 2021;37(2):319-328. doi:10.1016/j.cjca.2020.04.037Wu S, Chen X, Wang S, et al. Evaluation of the Criteria to Distinguish Left Bundle Branch Pacing From Left Ventricular Septal Pacing. JACC Clin Electrophysiol . 2021;7(9):1166-1177. doi:10.1016/j.jacep.2021.02.018Shimeno K, Tamura S, Hayashi Y, et al. Achievement Rate and Learning Curve of Left Bundle Branch Capture in Left Bundle Branch Area Pacing Procedure Performed to Demonstrate Output-Dependent QRS Transition.J Cardiovasc Electrophysiol . 2022Jastrzębski M, Kiełbasa G, Curila K, et al. Physiology-based electrocardiographic criteria for left bundle branch capture. Heart Rhythm . 2021;18(6):935-943. doi:10.1016/j.hrthm.2021.02.021Figure LegendsFigure 1: Permanent His Bundle PacingPanel A: A 12-lead electrocardiogram (EKG) shows baseline conduction in a patient with exertional intolerance. The PR interval is markedly prolonged and, with exercise, this patient developed AV block. A permanent His-bundle pacemaker was implantedPanel B: An EKG demonstrating permanent His-bundle pacing in the same patient as panel A. Selective His-bundle capture results in reproduction of the intrinsic QRS complex.Figure 2: Non-Selective Left Bundle Branch PacingA 12-Lead electrocardiogram showing non-selective left bundle branch pacing. The paced QRS morphology is not a direct match for native conduction and the QRS duration is longer than at baseline. However, conduction system capture was confirmed with an output dependent QRS morphology change.FiguresFigure 1: Permanent His-Bundle Pacing

This editorial discusses the report titled “Cardiac Resynchronization Therapy Response in Cardiac Sarcoidosis” by Shabtaie et al.

Title: Percutaneous Lead Extraction in Patients with Large Vegetations: Limiting our Aspirations.Robert D. Schaller, DO11The Section of Cardiac Electrophysiology, Cardiovascular Division, Department of Medicine, Hospital of the University of Pennsylvania, Philadelphia, PennsylvaniaFunding: This work was supported in part by the Mark Marchlinski EP Research & Education FundKey words: Lead extraction, vegetation, pulmonary embolism, thrombus, aspirationDisclosures: NoneWord count: 1547Transvenous lead extraction (TLE) in the 1960’s involved orthopedic-style pulley systems that joined the exposed portion of the lead to progressively heavier weights hanging from the bed. Sustained tension on the lead was maintained until the patient experienced discomfort, ventricular arrhythmias, or noticeable resistance developed, and was maintained for minutes to days. The location of the lead within the chest was monitored with daily chest radiographs and the ensuingbang of the weight hitting the floor of the intensive care unit signified case conclusion; at which point the patient was assessed. Complications were erratic and included lead laceration and possible migration, injury to the tricuspid valve (TV), myocardial avulsion, tamponade, and death.1 Due to the immature nature of the procedure at that time, it was relegated to infectious indications including lead-related endocarditis, at that time referred to as “catheter fever”.Contemporary TLE has evolved into a highly refined practice with a multitude of tools and predictable results, and procedural indications that now span infection, venous occlusion, management of redundant leads, and access to magnetic resonance imaging.2Procedural imaging with computed tomography (CT) and real-time ultrasound-based tools have similarly changed the TLE experience with identification of adhesions, thrombi, vegetations, and complications.3 Large lead-related masses have historically caused angst due to the possibility of being sheared off by the extraction sheath and embolizing to the lung, and still represent a relative contraindication to percutaneous TLE.2In this issue of the Journal of Cardiovascular Electrophysiology , Giacopelli, et al.4 present the outcomes of 25 consecutive patients (mean age 64 years, 68% male) including 5 with pacemakers, 10 with implantable cardioverter-defibrillators, and 10 with cardiac resynchronization therapy devices, who underwent TLE with vegetations ≥10 mm on transesophageal echocardiography (TEE). Contrast-enhanced CT was performed before and after TLE with 18 (72%) patients showing subclinical pulmonary embolism (PE). Vegetation size (median of 17.5 mm and maximum of 30 mm) did not differ in those with and without PE (20.0 mm vs. 14.0 mm, p=0.116). Complete TLE success was achieved in all patients with 76% requiring advanced tools and 2 needing femoral snaring, and there were no significant procedural complications. In the group with pre-TLE PE, a post-TLE scan confirmed the presence of PE in only 14/18 (78%) and there were no patients with new PE formation. During a median follow-up period of 19.4 months, no re-infection of the new implanted systems was reported and there were 5 deaths (20%); with no differences between the groups. The authors concluded that subclinical PE was common in this clinical scenario but did not influence the complexity or safety of the procedure.Several aspects of this paper warrant comment. No data are reported on the size or location of the PEs nor the time between the first and second CT. It is possible that small PEs would not be identified on subsequent studies days after antibiotics had already been started. Patients also received acute and chronic anticoagulation if PE was identified, which in the setting of vegetations, is generally not indicated and could potentially lead to bleeding. The authors did not provide information regarding infectious pathogens or the timing of culture clearance, which could influence treatment. Additionally, it is unclear which patients received new CIED systems including the type and timing of reimplantation, which might influence subsequent infectious risk. A vascular occlusion balloon was not used in any patients in this report. While this tool is associated with a reduced risk of death in the setting of a superior vena cava laceration when used properly, it has also been shown to be thrombogenic during long dwell times,5 and use could impact post-operative CTs in future studies. Despite utilizing transthoracic echocardiography during TLE, neither TEE nor intracardiac echocardiography were used intraoperatively and thus no information regarding the precise location of the vegetations within the heart is known. Importantly, no information regarding the characteristics of the vegetations other than size was reported.Not all lead-related masses are created equal with two distinct sub-types previously described.6 The first is composed of thickened endocardium and fibrous tissue covering the leads and ultimately forming into connective tissue. These masses, commonly found on leads behind the TV, are caused by a vortical flow pattern leading to low shear stress on the lead surface and provoking neointimal hyperplasia,7 and range from small fibrous strands to large, smooth organized thrombus (Figure, left column). Despite their sterile nature, TLE in the setting of a large, mature thrombus could result in embolization and obstruction of the pulmonary artery resulting in symptomatic PE. The second type, frequently seen in the setting of infective endocarditis, is composed of inflammatory cells, platelets, adhesion molecules, fresh fibrin, and bacteria binding to coagulum and forming vegetations. They are typically longer, more likely to be multi-lobular, and commonly span several chambers of the heart (Figure, right column). These vegetations that are typically acute, with friable finger-like projections, characteristically break apart upon being sheared off during TLE, with reports showing low risk of symptomatic PE.8 Vegetations that are lobular, however, have been associated with worse outcomes.9Despite acute procedural success in the setting of lead-related vegetations, mortality rates at 1 year approach 25%.10 Indeed, despite successful TLE in this report, 20% of patients were dead at 1.5 years. Although complete understanding of the mechanism of these poor outcomes remains unknown, septic emboli, lung abscesses, and infected lead “ghosts” have been implicated.11 Vegetation removal prior to TLE has thus represented an appealing therapeutic option with reports of successful percutaneous aspiration prior to TLE showing promising results, albeit with unknown long-term benefit.12,13 Although the lack of new PEs after TLE in this report does not directly support the effort, cost, and added risk of such a strategy, “debulking” of infectious burden remains a tempting complementary treatment. Importantly, the acute safety of TLE with large vegetations in this study should not be extrapolated to chronic, large lead-related masses, which are more like to cause acute PE if embolized. While aspiration of these sterile masses prior to TLE is appealing from a procedural outcome perspective, their morphologic characteristics, and the imperfect, but evolving, aspiration sheaths currently available are limiting, and requires consideration of surgical extraction. Further advancements in aspiration catheter technology and the development of right ventricular outflow track filters might influence future management.TLE continues to represent the gold standard for the management of lead-related infection.2 Due to the extensive work of the pathfinders in the vanguard of procedural development, the sound of crashing weights has been supplanted by those that power advancing sheaths. Yet despite the safe and predictable nature of modern-day TLE, the sobering long-term mortality of patients with infectious indications remains out of proportion to acute procedural success. While infectious “debulking” continues to represent the most attractive and practical complementary option to address this incongruity, future studies should concentrate both on identification of mass characteristics that suggest success, as well as determining if long-term benefits exist above and beyond lead removal. However, if improvement in clinical outcomes that warrant this added cost and effort are not identified, we should likely limit our aspirations.

CT-imaging vs. high-density mapping in ischemic cardiomyopathy VT ablation: in whom do we trust?Thomas Fink, MD1, Vanessa Sciacca, MD1, Philipp Sommer, MD11Clinic for Electrophysiology, Herz- und Diabeteszentrum NRW, Ruhr-Universität Bochum, Bad Oeynhausen, Germany.Disclosures: PS is advisory board member of Abbott, Biosense Webster, Boston Scientific and Medtronic.Funding: (None)

Aims The treatment with the wearable cardioverter defibrillator (WCD) may protect against sudden cardiac death (SCD) as a bridging therapy until a cardioverter-defibrillator may be implanted. We analyzed in a multicenter setting a consecutive patient cohort wearing WCD to explore gender differences. Methods and results We analyzed 708 consecutive patients, 579 from whom were males and 129 females (age, 60.5±14 vs. 61.6±17 years old; p=0.44). All patients were divided into age quartiles for analysis. While the rate of ischemic cardiomyopathy (ICM) as a cause of prescription of WCD was significantly higher in males as compared to females (42.7% vs. 26.4%; p=0.001), females received it more frequently due to non-ischemic cardiomyopathy (NICM) (55.8% vs. 42.7%); p=0.009). The wear time of WCD was equivalent in both groups (21.1±4.3 hours/days in males vs. 21.5±4.4 hours/days in females; p=0.27; and 62.6±44.3 days in males vs. 56.5±39 days in females; p=0.15). Mortality was comparable in both groups at 2-year-follow-up (6.8% in males vs. 9.7% in females; p=0.55). Appropriate WCD shocks and the incidence of device implantations were similar in both groups (2.4% in males vs. 3.9% in females; p=0.07) (35.1% in males vs. 31.8% in females; p=0.37), respectively. In age quartile analysis, compliance was observed more in older patients as compared to adult patients (87.8% vs. 68.3%; p<0.001). Conclusion Compliance for wearing WCD was excellent regardless of gender. Furthermore, mortality and the incidence of device implantations were comparable in both groups. Appropriate WCD shocks tended to be higher in females as compared to males.

Fetal atrioventricular block (AVB) is a failure of conduction from atria to ventricles. Immune- and non-immune-mediated forms occur, especially in association with congenital heart disease. Second-degree (2°) AVB may be reversible with dexamethasone and IVIG in immune-mediated disease. However, once third-degree AVB develops, it is deemed irreversible with need for a pacemaker and risk for cardiomyopathy. Rarely, 2° AVB is a transient, benign phenomenon in the immature conduction system. Few case series of transient AVB have been reported, but a management approach has not been defined. We report four patients with self-resolving, non-immune fetal AVB and outline a management strategy.

The Mini Electrode-equipped Catheter: Utility for Paroxysmal Supraventricular Tachycardia Ablation

Abstract: After several years with sobering experiences with electrogram-based AF ablation approaches, Seitz et al present with the VX1 software a reliable tool to map and ablate spatio-temporal dispersion. The presented multicenter study in persistent AF patients was conducted in 1 expert and 7 satellite centers with a total of 17 operators, using the VX1 software to detect and subsequently ablate spatiotemporal dispersion. While the AF termination rate (88%) and the freedom from AF in 12 months FU (82%) was very encouraging, the VX1 software, using AI enhanced electrogram adjudication, achieved very similar results in all centers, regardless of the centre’s or the operator’s experience. Thus, the biggest criticism of electrogram-based ablation strategies, i.e. the lack of reproducibility in “non-expert” centers, seems to be finally addressed.

A 13-year-old boy was hospitalized after a syncopal episode that occurred during exercise. He suddenly felt chest tightness, sweating and palpitations, followed by a transient loss of conciseness. Upon emergency medical team arrival, he was awake and oriented. Baseline ECG showed sinus rhythm at a rate of 98 bpm, with narrow QRS, and no signs of long QT, Brugada, or pre-excitation. Physical examination, blood tests, 24 hours Holter monitoring, transthoracic echocardiography and stress test were all within normal limits. Eight days later he experienced a second episode of palpitations while walking to school. ECG revealed regular wide complex tachycardia (WCT) at a rate of 200 bpm, with LBBB morphology that terminated with Adenosine (Figure 1). The clinical tachycardia was easily induced by programmed electrical stimulation (Figure 2A). Diagnostic electrophysiological maneuver (Figure 2B) was followed by successful ablation, during which a unique phenomenon was noted (Figure 3). What is the diagnosis of the tachycardia and what are the unique findings noted during and after ablation?

Mitigating Esophageal Injury after Atrial Fibrillation Ablation Guided by Ablation Index; CLOSEr to goalJason S. Chinitz, MD1 and Eli Q. Harris, MD21.South Shore University HospitalNorthwell HealthBay Shore, NY2. Nassau University Medical CenterEast Meadow, NYFinancial support : none.Disclosures : Dr. Chinitz serves on the scientific advisory board for Biosense Webster and has received consulting fees

Background: The novel method of left bundle branch pacing (LBBP) has been reported to achieve better electrical and mechanical synchrony in the left ventricle than conventional right ventricular pacing (RVP). However, its effects on right ventricle (RV) performance are still unknown. Methods: Consecutive patients undergoing dual-chamber pacemaker (PM) implantation for sick sinus syndrome (SSS) with normal cardiac function and a narrow QRS complex were recruited for the study. The pacing characteristics and echocardiogram parameters were measured to evaluate RV function, interventricular and RV synchrony, and were compared among ventricular pacing‐on and native‐conduction modes. Results: A total of 84 patients diagnosed with SSS and an indication for pacing therapy were enrolled. Forty-two patients (50%; mean age 65.50 ± 9.30 years; 35% male) underwent successful LBBP and 42 patients (50%; mean age 69.26 ± 10.08 years; 33% male) RVSP, respectively. Baseline characteristics were similar between the two groups. We found no significant differences in RV function [RV-FAC (Fractional Area Change)%, 47.13±5.69 vs. 48.60±5.83, p=.069; Endo-GLS (Global Longitudinal Strain)%, -28.88±4.94 vs. -29.82±5.35, p=.114; Myo-GLS%, -25.72±4.75 vs. -25.72±5.21, p=.559; Free Wall St%, 27.40±8.03 vs. -28.71±7.34, p=.304] between the native‐conduction or LBBP capture modes, while the RVSP capture mode was associated with a significant reduction in the above parameters compared with the native‐conduction mode (P < .0001). The interventricular synchrony in the LBBP group was also superior to the RVSP group significantly. Conclusion: LBBP is a pacing technique that seems to associate with a positive and protective impact on RV performance.

Background: Epicardial pacemakers are known as an alternative for endocardial pacemakers in some cases such as heart block, and complex congenital heart diseases. Considering recent advances and improvement of epicardial lead subtypes, it is essential to investigate the long-term function of them. In this study, we aimed to assess the sensing and pacing characteristics, and survival of bipolar steroid-eluting and unipolar non-steroid-eluting epicardial pacemakers. Methods: We conducted an entirely concentrated search on the documents of all patients who had undergone epicardial lead implantation in the Shaheed Rajaie Cardiovascular, Medical & Research Center during 2015-2018. Implant, and follow up data were extracted. Kaplan Meier analysis and Weibull regression hazards model were applied for the survival analysis. Results: eighty-nine leads were implanted for 77 patients. Of the total leads, 52.81%, 53.93%, and 47.19% were implanted in children (under-18-year-old), females, and patients with congenital heart diseases, respectively. Bipolar steroid-eluting leads comprised 33.71% of 89 leads. Pacing threshold of unipolar non-steroid-eluting leads that were implanted on the left ventricle and right atrium increased significantly during the follow up to greater records than bipolar steroid-eluting leads. Survival analysis also revealed that bipolar steroid-eluting leads are significantly better in 48-month survival (Weibull HR: 0.13 (95%CI, 0.02-0.99), p-value, 0.049). Age, ventricular location of the lead, and acute pacing characteristics were not associated with survival. Conclusions: Bipolar steroid-eluting epicardial leads have an acceptable survival compared with unipolar non-steroid-eluting, without a significant difference regarding patients age. Therefore, they could be an excellent alternative for endocardial ones.