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The human cardiac sodium channel (hNav1.5, encoded by the SCN5A gene) is critical for action potential generation and propagation in the heart. Drug-induced sodium channel inhibition decreases the rate of cardiomyocyte depolarization and consequently conduction velocity and can have serious implications for cardiac safety. Genetic mutations in hNav1.5 have also been linked to a number of cardiac diseases. Therefore, off-target hNav1.5 inhibition may be considered a risk marker for a drug candidate. Given the potential safety implications for patients and the costs of late stage drug development, detection and mitigation of hNav1.5 liabilities early in drug discovery and development becomes important. In this review, we describe a preclinical strategy to identify hNav1.5 liabilities that incorporates in vitro, in vivo, and in silico techniques and the application of this information in the integrated risk assessment at different stages of drug discovery and development.

Aim: A recent European Heart Rhythm Association (EHRA) practical guide provides guidance on the use of novel digital devices for heart rhythm analysis using either electrocardiogram (ECG) or photoplethysmography (PPG) technology for the diagnosis of atrial fibrillation (AF). This survey assesses physicians' preferences to use digital devices in patients with possible AF and their impact on clinical decision-making., Methods and Results: Participants of the DAS-CAM III initiated and distributed an online survey assessing physician preferences in using digital devices for the management of AF in different clinical scenarios. A total of 505 physicians (median age: 38 [IQR 33-46] years) from 30 countries completed the survey. A third of respondents were electrophysiologists, the others were cardiologists, cardiology residents, or general practitioners. Electrophysiologists were more likely to have experience with both ECG-based (92% vs. 68%, p < 0.001) and PPG-based (60% vs. 34%, p < 0.001) digital devices. The initial diagnostic approach to each scenario (symptomatic low-risk, symptomatic high-risk, or asymptomatic high-risk patient) was heterogeneous. Electrophysiologists preferred intermittent single-lead ECG monitoring to traditional Holter ECGs to screen for AF. Both electrophysiologists and non-electrophysiologists would rarely use PPG-based devices to diagnose and screen for AF (8.2%-9.8%). Electrophysiologists and non-electrophysiologists use ECG-based technology to confirm PPG-documented tracings suggestive of AF., Conclusion: While PPG-based digital devices are rarely used for diagnosis and screening for AF, intermittent ECG-based digital devices are beginning to be implemented in clinical practice. More education on the potential of novel digital devices is required to achieve diagnostic pathways as suggested by the EHRA practical guide., (© 2024 The Author(s). Clinical Cardiology published by Wiley Periodicals, LLC.)

Persistent left superior vena cava (PLSVC) is one of the anatomical variations, which can make device implantation more challenging and lead to incorrect lead placement, dislodgement, and procedure failure. Conduction system pacing (CSP) can be an alternative to traditional CRT implantation. Herein, we describe a brief case report of successful LBBAP-optimized CRT (LOT-CRT) via an innominate vein in a patient with PLSVC., (© 2024 Wiley Periodicals LLC.)

Background: Permanent pacing is often required following valve intervention (either surgical or percutaneous); however, tricuspid interventions pose specific challenges to conventional pacing. Therefore, leadless pacemaker (LP) implantation may be the preferred strategy when permanent pacing is required after tricuspid valve intervention., Purpose: To report periprocedural outcomes and follow-up of patients undergoing implantation of a LP system following tricuspid valve interventions., Methods: Patients with previous tricuspid valve intervention at the time of attempted implantation of a LP (MicraTM, Medtronic, Minneapolis, MN, USA) were included., Results: Between 2019 and 2022, 40 patients underwent LP implantations following tricuspid interventions in 5 large tertiary centers. The mean age was 68.9 ± 13.7 years, and 48% patients were male. The indication for pacing was as following: AVB in 27 (68%) patients, AF with slow ventricular response in 10 (25%) patients, and refractory rapid atrial fibrillation (AF) referred to AV junction ablation in 3 (7%) patients. Most of the patients received Micra VR (78%). The procedure was successful in all patients. The mean procedural time is 58 ± 32 min, and the median fluoroscopy time is 7.5 min. Electrical parameters were within normal range (threshold: 1.35 ± 1.2 V@0.24 ms, impedance: 772 ± 245 Ohm, R-wave: 6.9 ± 5.4 mV). No acute complications were observed. During a mean follow-up of 10 months, electrical parameters remained stable, and 4 deaths were occurred (not related to the procedure)., Conclusion: A LP is a safe and efficient option following tricuspid valve interventions., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Aims: Prior case series showed promising results for cardioneuroablation in patients with vagally induced atrioventricular blocks (VAVBs). We aimed to examine the acute procedural characteristics and intermediate-term outcomes of electroanatomical-guided cardioneuroablation (EACNA) in patients with VAVB., Methods and Results: This international multicentre retrospective registry included data collected from 20 centres. Patients presenting with symptomatic paroxysmal or persistent VAVB were included in the study. All patients underwent EACNA. Procedural success was defined by the acute reversal of atrioventricular blocks (AVBs) and complete abolition of atropine response. The primary outcome was occurrence of syncope and daytime second- or advanced-degree AVB on serial prolonged electrocardiogram monitoring during follow-up. A total of 130 patients underwent EACNA. Acute procedural success was achieved in 96.2% of the cases. During a median follow-up of 300 days (150, 496), the primary outcome occurred in 17/125 (14%) cases with acute procedural success (recurrence of AVB in 9 and new syncope in 8 cases). Operator experience and use of extracardiac vagal stimulation were similar for patients with and without primary outcomes. A history of atrial fibrillation, hypertension, and coronary artery disease was associated with a higher primary outcome occurrence. Only four patients with primary outcome required pacemaker placement during follow-up., Conclusion: This is the largest multicentre study demonstrating the feasibility of EACNA with encouraging intermediate-term outcomes in selected patients with VAVB. Studies investigating the effect on burden of daytime symptoms caused by the AVB are required to confirm these findings., Competing Interests: Conflict of interest: none declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Pacing-induced cardiomyopathy (PICM) is defined as a drop in left ventricular ejection fraction (LVEF) in the setting of chronic, high-burden right ventricular pacing. Cardiac resynchronization therapy (CRT) and conduction system pacing (CSP) have been proposed to manage PICM. Although acute myocardial infarction has been described as a predictor of PICM, there are no guideline recommendations for CRT or CSP in patients with coronary artery disease (CAD) and preserved LVEF. In this report, we present and discuss three cases of PICM in patients with CAD and preserved LVEF., Competing Interests: The authors report no conflicts of interest for the published content. No funding information was provided., (Copyright: © 2024 Innovations in Cardiac Rhythm Management.)

A 58-year-old man admitted for a cryoballoon ablation due to a history of symptomatic paroxysmal atrial fibrillation experienced pericardial effusion and cardiac tamponade intraoperatively. A longitudinal left superior pulmonary vein perforation was confirmed by emergency thoracotomy and repaired. He developed atrial fibrillation 2 days postoperatively, which was terminated with colchicine and oral steroids the following day., Competing Interests: The authors report no conflicts of interest for the published content. No funding information was provided., (Copyright: © 2023 Innovations in Cardiac Rhythm Management.)

Brugada phenocopy (BrP) is a clinical condition characterized by transient ECG changes of Brugada syndrome (BrS), which can be due to various clinical conditions. We describe a case report of BrP due to psychotic drugs., Competing Interests: Declaration of Competing Interest All authors declare that the manuscript, as submitted or its essence in another version, is not under consideration for publication elsewhere, and it will not be submitted elsewhere until a final decision is made by the editors of the Journal of Electrocardiology. The authors have no commercial associations or sources of support that might pose a conflict of interest. All authors have made substantive contributions to the study, and all authors endorse the data and conclusions., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Brugada phenocopies (BrP) represent electrocardiogram changes identical to those of true congenital Brugada syndrome but are induced by reversible clinical conditions. Previous cases have been reported in patients following recreational drug use. This report presents two cases of type 1B BrP associated with Fenethylline abuse, a recreational drug known by its trade name, Captagon., Competing Interests: Declaration of Competing Interest All authors declare that the manuscript, as submitted or its essence in another version, is not under consideration for publication elsewhere, and it will not be submitted elsewhere until a final decision is made by the editors of the Journal of Electrocardiology. The authors have no commercial associations or sources of support that might pose a conflict of interest. All authors have made substantive contributions to the study, and all authors endorse the data and conclusions., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Left ventricular lead positioning is technically demanding in cardiac resynchronization therapy (CRT) device implantation, especially in patients with complex cardiac venous anatomies. We report a case in which retrograde snaring was employed to successfully deliver the left ventricular lead through a persistent left superior vena cava for CRT implantation., Competing Interests: The authors report no conflicts of interest for the published content. No funding information was provided., (Copyright: © 2023 Innovations in Cardiac Rhythm Management.)

Background: The reported success rate of His-bundle pacing (HBP) in patients with infranodal atrioventricular (AV) conduction disease is only 52%-76%. The success rate of left bundle branch area pacing (LBBAP) in this cohort is not well studied., Objective: The purpose of this study was to evaluate the feasibility, safety, and electrophysiological characteristics of LBBAP in patients with AV conduction disease., Methods: Patients with AV conduction disease referred for pacemaker implantation at 2 centers between February 2019 and June 2021 were considered for LBBAP. Baseline demographic characteristics, procedural success rates, electrophysiological parameters, and complications were assessed., Results: LBBAP was successful in 340 of 364 patients (93%). Mean age was 72 ± 13 years, and mean follow-up was 331 ± 244 days. Pacing indications were Mobitz I in 27 patients (7%), Mobitz II or 2:1 AV block or high-grade AV block in 94 patients (26%), complete heart block in 199 patients (55%), and sick sinus syndrome with isolated bundle branch block in 44 patients (12%). Left bundle branch block and right bundle branch block were present in 57 patients (16%) and 140 patients (38%), respectively. Procedural success rates did not differ between indications (92.6%, 93.6%, 92.9%, and 95%, respectively) or between patients with narrow (<120 ms) vs wide QRS (≥120 ms). Mean LBBAP threshold was 0.77 ± 0.34 V at 0.4 ms at implant and remained stable during follow-up. There were 4 (1.2%) acute LBBAP lead dislodgments., Conclusion: LBBAP is safe and feasible with high success rates for patients with AV conduction disease. In contrast to HBP, LBBAP success rates remain high over the entire spectrum of AV conduction disease, and lead parameters remain stable during follow-up., (Copyright © 2022 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.)

Background: Ablation index (AI) is a novel catheter-based parameter that has improved the outcome and safety of radiofrequency (RF) ablation of pulmonary vein isolations (PVIs). This index incorporates contact force (CF) (g), time (s), and power (W) parameters. The role of AI in redo ablations for persistent atrial fibrillation (peAF) has not been fully investigated. Hence, the impact of AI on the success of the redo PVI during the short-term follow-up period is the aim of this study., Methods: A retrospective analysis of 39 consecutive patients who underwent redo PVI ablations for peAF was carried out between January 2016 and December 2018. Target values for AI were 500 - 550 for anterior and roof and 400 - 380 for posterior and inferior regions. We compared outcomes between AI-guided and catheter CF ablations (i.e., forced time integral (FTI) of more than 400 g/s) during a follow-up of 24 months., Results: Pulmonary vein reconnections at redo procedure were similar in both groups (P = 0.1). AF free burden period was non-significant (mean 15.53 ± 2.4 months in AI group vs. 15.22 ± 1.9 months in CF group, P = 0.79) at 24 months. The AI group demonstrated greater numbers of patients for whom anti-arrhythmic therapy could be de-escalated over 1 year (n = 11 (65%) in AI vs. n = 6 (27%) in CF, P = 0.02). Fewer patients underwent escalation of their anti-arrhythmic therapy (n = 2 (12%) in AI vs. n = 7 (32%) in CF, P = 0.15). The AI group trended towards a shorter procedure time (111.6 ± 27 min) compared to the CF group (133 ± 40 min) (P = 0.06). Other procedural details were comparable., Conclusion: Redo PVI interventions using AI lead to a significant de-escalation in medication during follow-up. Procedure time and radiation dose using AI tends to be shorter. Both techniques are safe with minimal complications., Competing Interests: Limited financial support from J&J to cover the publication fee of the manuscript., (Copyright 2022, Lennon et al.)

Objectives: To evaluate the safety and feasibility of left bundle branch area pacing (LBBAP) in patients with valvular interventions., Methods: Eighty-four patients were included in this study. All patients underwent recent surgical or percutaneous valvular interventions. LBBAP was attempted in all patients. Implant success rates, peri- and postprocedure electrocardiogram, pacing parameters, and complications were assessed at implant, and during follow-up., Results: LBBAP implantation was successful in 80/84 (95%) patients. Mean age was 74.1 ± 13.8 years and 56% patients were male. Prior valvular replacements included: percutaneous aortic (26), surgical aortic (36), combined surgical aortic plus mitral (6), MVR (10), tricuspid (1), and pulmonic (1). Average LVEF was 52.6 ± 11%. Majority of patients underwent LBBAP due to atrioventricular block (76%) and sinus node disease (13%). Total procedure duration was 74.1 ± 12.5 min and fluoroscopic duration was 9.7 ± 6.8 min. Pacing parameters were stable during follow-up period of 10.0 ± 6.3 months. Pacing QRS duration was significantly narrower than baseline QRS duration (131.5 ± 31.4 ms vs. 114.3 ± 13.7 ms, p < .001, respectively). No acute complications were observed. Mean follow-up was 10.0 ± 6.3 months (median: 8.4 months, min: 1 and max: 24 months). During follow-up, there were three device infections and two patients had loss of LBBA capture within 1 month of implant., Conclusions: LBBAP is a feasible and safe pacing modality in patients with prior interventions for valvular heart disease., (© 2021 Wiley Periodicals LLC.)

Accessory pathways (APs) are commonly located around the tricuspid and mitral annulus; however, they can be rarely seen in unusual locations like the aortomitral continuity (AMC), the right atrium to the right ventricular outflow region, and the left atrial appendage to left ventricle connection. Although several electrocardiogram algorithms have been proposed to localize the AP, the sensitivity of these algorithms is not high and they may fail to localize the mentioned unusual localizations. In this report, we describe a case of a 37-year-old man presenting with an AP originating from the AMC, which was successfully ablated., Competing Interests: The authors report no conflicts of interest for the published content., (Copyright: © 2021 Innovations in Cardiac Rhythm Management.)

Atrial fibrillation (AF) ablation has been shown to be an effective treatment for AF, although our understanding of AF ablation outcomes until now, has been based on AF recurrence as a dichotomous variable. Reduction in AF burden, defined as the proportion of time that an individual is in AF during a monitoring period, has been already correlated to an improvement in quality of life and is likely a better assessment of success. Clinically, many patients may still have a few short recurrences of AF but feel much better. In addition, several studies have related higher AF burden with poorer health outcomes and a higher risk of stroke. Despite the growing understanding of AF burden, it is not clear yet which threshold of AF burden would be considered an appropriate outcome measure for AF ablation. Further investigations are needed to address that question. However, the reduction of AF burden seems to be a more accurate reflection of procedural success and a better predictor of prognosis and stroke risk than a single measure of AF., Competing Interests: Dr. Atul Verma report the grant, personal fees, clinical trial from Medtronic, Biosense Webster, Bayer, Medlumics, and Adagio Medical. The other authors have no financial conflicts of interest., (Copyright © 2021. The Korean Society of Cardiology.)

Background: Coronavirus disease 2019 (COVID-19) primarily causes lung infection, but recent studies have shown that cardiac involvement is associated with a worse prognosis., Objectives: We conducted a systematic review and meta-analysis to examine the prevalence of cardiac arrhythmias detected by the electrocardiogram and their relationships with adverse outcomes in patients with COVID-19., Methods: PubMed and Google were searched for studies that reported on cardiac arrhythmias and/or examined the relationship between arrhythmias and adverse outcomes., Results: Thirty studies with 12,713 participants were included in the systematic review, and 28 studies (n = 12,499) in the meta-analysis. The mean age was 61.3 ± 16.8 years; 39.3% were female. In 25 studies with 7578 patients, the overall prevalence of cardiac arrhythmias was 10.3% (95% confidence interval [CI]: 8.4%-12.3%). The most common arrhythmias documented during hospitalization were supraventricular arrhythmias (6.2%, 95% CI: 4.4%-8.1%) followed by ventricular arrhythmias (2.5%, 95% CI: 1.8%-3.1%). The incidence of cardiac arrhythmias was higher among critically ill patients (relative risk [RR]: 12.1, 95% CI: 8.5-17.3) and among non-survivors (RR: 3.8, 95%, CI: 1.7-8.7). Eight studies reported changes in the QT interval. The prevalence of QTc > 500 ms was 12.3% (95% CI: 6.9%-17.8%). ST-segment deviation was reported in eight studies, with a pooled estimate of 8.7% (95% CI: 7.3% to 10.0%)., Conclusion: Our meta-analysis showed that QTc prolongation, ST-segment deviation, and various other cardiac arrhythmias were observed in patients hospitalized with COVID-19. The presence of cardiac arrhythmias was associated with a worse prognosis., (© 2021 Wiley Periodicals LLC.)

Leadless pacemakers have become an effective alternative to conventional transvenous pacemakers to prevent the risk of lead failure, pocket complications, and iatrogenic tricuspid regurgitation. The current transcatheter approach for tricuspid valve repair can limit the implantation of these devices, unless the procedure is performed with appropriate image guidance. We present the case of a patient with severe tricuspid regurgitation secondary to pacemaker lead impingement who, despite the implantation of a tricuspid clip, received a leadless pacemaker. The procedure was successfully guided by transthoracic echocardiography, an alternative to transesophageal or intracardiac echocardiography., (© 2021 The Authors.)

Objectives: This multicenter registry aimed to assess the reproducibility and safety of intentional coronary vein exit and carbon dioxide insufflation to facilitate subxiphoid epicardial access in the setting of ventricular tachycardia ablation., Background: Epicardial ablation for ventricular tachycardia is not a widespread technique due to the significant potential complications associated with subxiphoid puncture. The first experience in 12 patients showed that intentional coronary vein exit and carbon dioxide insufflation was technically feasible., Methods: A branch of the coronary sinus was cannulated by means of a diagnostic JR4 coronary catheter. Intentional perforation at the distal portion of that branch was performed with a high tip load 0.014-inch angioplasty wire. A microcatheter was advanced over the wire into the pericardial space. Carbon dioxide was then insufflated into the pericardial space, allowing direct visualization of the anterior pericardial space to facilitate subxiphoid puncture., Results: Intentional coronary vein exit was attempted in 102 consecutive patients in 16 different centers and successfully completed in 101 patients. Significant pericardial adhesions were confirmed in 3 patients, preventing carbon dioxide insufflation and epicardial ablation. None of the punctures were complicated with inadvertent right ventricular puncture or damage to a coronary artery. Significant bleeding (>80 ml) due to coronary vein exit occurred in 5 patients, without hemodynamic compromise. None of the patients required surgery., Conclusions: Coronary vein exit and carbon dioxide insufflation can be safely and reproducibly achieved to facilitate subxiphoid pericardial access in the setting of ventricular tachycardia ablation., Competing Interests: Author Disclosures The authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Left bundle branch block (LBBB) can result in significant dyssynchrony in left ventricular (LV) contraction, ultimately leading to cardiac remodeling. LBBB can be rate dependent and may appear with LV systolic dysfunction. Cardiac resynchronization therapy (CRT) has been demonstrated to improve hemodynamics as well as clinical symptoms in patients with LBBB. We describe the case of a 57-year-old man who underwent CRT implantation due to exertional dyspnea, rate-dependent LBBB, and impaired left LV systolic function., (© 2020 Wiley Periodicals LLC.)

In December 2019, reports of an unknown pneumonia not responsive to traditional treatments arose in Wuhan, China. The pathogen was subsequently identified as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), known to be responsible for the coronavirus disease-2019 (COVID-19) illness, and public health emergency of international concern was declared by the World Health Organization. There is increasing awareness of the cardiovascular manifestations of COVID-19 disease, and the adverse impact of cardiovascular involvement on its prognosis. In this setting, the electrocardiogram (ECG) is one of the leading tools to assess the extent of cardiac involvement in COVID-19 patients, due to its wide disponibility, low cost, and the possibility of remote evaluation. In this article, we review the role of the ECG in the identification of cardiac involvement in COVID-19, highlighting relevant clinical implications., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Leadless pacemakers provide a potential alternative to conventional transvenous pacemakers for patients undergoing high-risk transcatheter valve replacement procedures. This is a description of a successful leadless pacemaker implantation in a 51-year-old woman who developed profound bradycardia following a transcatheter aortic valve replacement and mitral valve-in-valve procedure.

BACKGROUND The occurrence of ventricular arrhythmias (VAs), particularly premature ventricular complexes, following pulmonary vein isolation (PVI) is a documented phenomenon, but monomorphic scar-related ventricular tachycardia (VT) following PVI is an unusual phenomenon. In this case report, we present a case of new-onset VA after radiofrequency PVI in a patient with no prior history of sustained VTs. CASE REPORT Our patient was a 69-year-old man with a history of symptomatic persistent atrial fibrillation, with an apparently structurally normal heart with subtle regional wall motion abnormalities. He underwent radiofrequency directed pulmonary vein isolation ablation. On the night of an uneventful procedure, the patient for the first time experienced a sustained ventricular tachycardia that exacerbated into a VT storm. Each arrhythmia was terminated by cardioversion due to hemodynamic instability. Antiarrhythmic treatment with lidocaine was initiated immediately. The patient settled from sustained ventricular arrhythmia and received further ablation to monomorphic ventricular tachycardia. CONCLUSIONS The incidence of ventricular ectopics after PVI ablation has been previously described, but a sustained monomorphic ventricular storm has not been reported before with RF ablation. We attribute the pathophysiology to an increase in myocardial excitability and/or ventricular autonomic modulation. This is a very rare phenomenon, but any subtle imaging abnormality before planning RF-PVI should be taken into consideration.

Left septal fascicular block, or blockage of the middle fibers of the left bundle branch, is known to be suggestive of a critical proximal obstruction of the left anterior descending coronary artery before its first septal perforator branch. We describe the case of a 68-year-old male who exhibited this transient intraventricular dromotropic disturbance following alcohol septal ablation for hypertrophic obstructive cardiomyopathy.

Aims: Substrate based catheter ablation strategies are widely employed for treatment of scar-related ventricular tachycardia (VT). We analysed intracardiac electrograms (EGMs) from close-coupled paced extrastimuli extracted from the EnSite Precision mapping system. We sought to characterize EGM responses of ventricular myocardium to varying coupling intervals from the right ventricular apex (RVA) in both healthy individuals and patients presenting with VT for catheter ablation., Methods and Results: Extrastimuli were delivered from the RVA after estimation of the ventricular effective refractory period. Electrograms were recorded from high-density mapping catheters in the left ventricle and exported for analysis to MATLAB. Observational data were collected from 14 patients with ischaemic VT (mean age 72.4 ± 6.3 years, one female) and five controls (mean age 59.4 ± 7.4 years, one female). These derived data were used to inform an interventional strategy on a further 10 patients (mean age 64.7 ± 10.0 years; two female). Significant differences were observed in EGM duration (ED) and latency (LT) at all coupling intervals between VT patients and controls. Significant increases in ED and LT with decreased RVA coupling interval were observed at VT isthmuses. Abnormal responses derived from control subject data were used to classify four types of ventricular EGM response. Targeting sites with abnormal LT and ED significantly reduced VT inducibility (5/14 derivation patients to 0/10 intervention patients; P = 0.03)., Conclusion: Paced electrogram feature analysis is a novel tool to characterize the ischaemic substrate. Association with VT isthmuses and early ablation results suggest a possible role in substrate ablation for ischaemic VT., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.)

Objective: A 12-lead electrocardiography is a critical component for the screening of long QT syndrome; however, besides, an electrocardiograph, trained personnel are also necessary which limits the screening capability of conventional electrocardiographs. The development of smartphone electrocardiography technologies provides a potential alternative platform for electrocardiography screening for selective purposes such as arrhythmias and QT interval abnormalities. The aim of this pilot study was to assess the reliability of a smartphone-based electrocardiography device in the measurement of QT and corrected QT intervals in children., Methods: In all participants, 10-s smartphone electrocardiography tracing from AliveCor device and a standard 12-lead electrocardiograph were obtained simultaneously. Two pediatric electrophysiologists performed the measurements of QT and corrected QT intervals in a blinded manner with Bazett's formula. The results were compared statistically., Results: A total of 285 children (mean age 9.8±4.9 years) who presented to our clinic were included in the study. The mean QT intervals obtained from 12-lead electrocardiographs and AliveCor devices were 343±40 ms and 340±41 ms, respectively. The mean corrected QT intervals obtained from 12-lead electrocardiographs and AliveCor devices were 419±28 ms and 415±33 ms, respectively. There was high correlation between the QT intervals of 12-lead electrocardiographs and AliveCor recordings (Pearson's correlation coefficient: 0.83 [p<0.001]) and significant correlation between the corrected QT intervals of 12-lead electrocardiographs and AliveCor recordings (Pearson's correlation coefficient: 0.57 [p<0.001])., Conclusion: AliveCor recordings can accurately detect QT intervals and can potentially be used for the screening of congenital long QT syndrome in children., Competing Interests: Conflict of Interest: No conflict of interest was declared by the authors.

Venous revascularization is an approach used in patients with total venous occlusion requiring venous access for cardiac device lead placement. Several percutaneous approaches to venous revascularization have been proposed. For the first time, we describe the case of a 69-year-old male with total venous occlusion who was successfully revascularized using a 'diathermy' technique., (Copyright © 2019 Indian Heart Rhythm Society. Production and hosting by Elsevier B.V. All rights reserved.)

Brugada phenocopies (BrP) are clinical entities that are characterized by ECG patterns identical to those of Brugada syndrome, but are the result of various clinical conditions. We describe the case of a 41-year-old male who exhibited BrP due to a left ventricular aneurysm in the context of chronic coronary artery disease., (Copyright © 2018. Published by Elsevier Inc.)

A 56-year-old male who had previously received an implantable cardioverter-defibrillator for primary prevention was admitted to the hospital with frequent shocks. Device interrogation revealed ineffective shock deliveries. Possible explanations for failed treatment are discussed herein., Competing Interests: The authors report no conflicts of interest for the published content., (Copyright: © 2018 Innovations in Cardiac Rhythm Management.)

Background: Catheter ablation is a cornerstone treatment strategy in atrial fibrillation (AF). Left atrial (LA) size is one of the contributors in development of AF recurrences. The impact of contact-forced (CF) guided catheter ablation on the success rate of persistent AF patients with severe enlarged LA has not been investigated yet., Methods: Sixty-six patients with diagnosis of longstanding persistent AF undergoing catheter ablation were enrolled. All patients underwent a standard transthoracic echocardiography according to the guidelines. LA size was considered severely enlarged when LA diameter was ≥ 50 mm. CF catheter ablation with a Tacticath Quartz catheter (St Jude Medical, St. Paul, MN, USA) was used in all patients., Results: The mean age was 61.9 ± 9.9 years, and LAD 47.8 ± 11.6 mm. Among 66 patients with persistent AF, 32 (48%) patients were diagnosed with AF recurrences. Twenty-eight (42%) patients had severely enlarged LA. The recurrence of AF was comparable in patients with and without severe enlarged LA (47% vs. 42%, p=0.79). The recurrence of AF was lower in patients who underwent CF-guided ablation with a normal LA dimension (36 %, p=0.54). Procedure duration was longer in patients with severely enlarged LA. LA dimension was not significantly different between patients with and without AF recurrence (49.8 ± 7.9 mm vs. 45.9 ± 7.5 mm, p=0.15). LAD and was significantly correlated with the time to recurrence of AF (r:-0.60, p=0.02)., Conclusion: Our preliminary findings have demonstrated that CF guided ablation does not improve the success rate in longstanding persistent AF patients with severe LA enlargement.

Background: Complex fractionated electrograms (EGMs) of the coronary sinus electrograms (CSEs) are employed as a target during radiofrequency ablations (RFA) of atrial fibrillation (AF). Anatomically, CSEs includes both of left atrium (LA), coronary sinus musculature and right atrium (RA) electrograms., Aim: To determine the significance of fractionated CSE and delayed potentials as a predictor of new-onset AF after radiofrequency ablation (RFA) of isolated atrial flutter (AFL)., Methods: Consecutive patients underwent AFL ablation. Fractionated and/or continuous discrete activities were recorded from coronary sinus electrograms during sinus rhythm and during pacing. Earliest CSE to the S nadir or peak R in milliseconds was recorded and considered as propagation delay for EGMs., Results: Forty patients were included during a mean follow-up period of 55.1± 15.8 months. Twenty patients (50 %) developed AF while the remaining 20 patients maintained sinus rhythm(SR) during the follow-up period. Proximal and mid CSEs were significantly fractionated in AF group compared to group with no AF development (65 % and 60% Vs. 35 % and 30 %, p = 0.03, respectively). However, during pacing from distal duo-decapolar catheter (pole 1-2), distal CSEs alone were significantly fractionated (p < 0.05) compared to SR group. Significant delayed propagation of proximal CSE during pacing and in sinus rhythm were observed in AF group (12.3 ± 9.2 ms vs 7.1 ± 3.6 ms, p = 0.03) and (7.2 ± 2.9 ms Vs 8.1 ± 4.6 ms, p= 0.02) in the same order., Conclusion: Incidence of AF is associated with fractionated proximal and mid CSE in sinus rhythm and distal CSE during paced rhythm after isolated AFL ablation. Delayed proximal CSE propagation is correlated with AF incidence.

Ventricular arrhythmias are life-threatening and can serve as a precursor to sudden death. They are a common presentation in patients with severely reduced left ventricular (LV) function. The use of an implantable cardioverter defibrillator (ICD) is seen as an acceptable therapy against malignant ventricular arrhythmias. In patients with LV heart failure, a left ventricular assist device (LVAD) can provide pulsatile flow to mimic the cardiac systolic and diastolic function. We report a case of a 38-year-old male with a LVAD who presented to the emergency department due to syncope and frequent ICD discharges. There were documented episodes of ventricular fibrillation and a failed defibrillator threshold test.

Background: Current algorithms and device morphology templates have been proposed in current Implantable Cardioverter-Defibrillators (ICDs) to minimize inappropriate therapies (ITS), but this has not been completely successful., Aim: Assess the impact of a deliberate strategy of using an atrial lead implant with standardized parameters; based on all current ICD discriminators and technologies, on the burden of ITS., Method: A retrospective single-centre analysis of 250 patients with either dual chamber (DR) ICDs or biventricular ICDs (CRTDs) over a (41.9 ± 27.3) month period was performed. The incidence of ITS on all ICD and CRTD patients was chronicled after the implementation of standardized programming., Results: 39 events of anti-tachycardial pacing (ATP) and/or shocks were identified in 20 patients (8% incidence rate among patients). The total number of individual therapies was 120, of which 34% were inappropriate ATP, and 36% were inappropriate shocks. 11 patients of the 250 patients received ITS (4.4%). Of the 20 patients, four had ICDs for primary prevention and 16 for a secondary prevention. All the episodes in the primary indication group were inappropriate, while seven patients (43%) of the secondary indication group experienced inappropriate therapies., Conclusions: The burden of ITS in the population of patients receiving ICDs was 4.4% in the presence of atrial leads. The proposed rationalized programming criteria seems an effective strategy to minimize the burden of inappropriate therapies and will require further validation., (Copyright © 2017 Indian Heart Rhythm Society. All rights reserved.)

"Spiked helmet" is a type of ST elevation, which is generally observed in critically ill patients and associated with very poor prognosis. Here we present a case of previously undiagnosed long QT syndrome admitted with polymorphic ventricular tachycardia (PMVT) unresponsive to pharmacological treatment and developed "spiked helmet" sign after left percutaneous stellate ganglion ablation., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Due to its safety profile, cryoablation (Cryo) for atrioventricular nodal reentrant tachycardia (AVNRT) is more commonly preferred over radiofrequency (RF) ablation in children in recent years. Recent studies demonstrated high long-term success rates comparable to radiofrequency ablation. The aim of this prospective study was to compare the efficacy and safety of an 8-mm-tip versus 6-mm-tip Cryo catheter in the treatment of AVNRT in children. A total of 125 consecutive patients over 10 years of age with AVNRT were included. EnSite system (St. JudeMedical, St Paul, MN, USA) was used to reduce or eliminate fluoroscopy. The acute procedural success was 100% in both groups. The prodecure duration for the 8-mm-tip group was shorter (151.6 ± 63.2 vs. 126.6 ± 36.7 min, p < 0.01, respectively). Fluoroscopy was used in only 7 patients. The mean follow-up duration was 14.6 ± 8.4 months (median 13.5 months, min. 3 months and max. 27 months). The recurrence rate for AVNRT was also comparable between the two groups (6-mm tip: 9.6 vs. 8-mm tip: 8%). Cryo of AVNRT is a safe and effective procedure with comparable acute and mid-term follow-up success rates using 6-mm and 8-mm-tip catheters in children. In addition, procedure duration is shorter with an 8-mm-tip Cryo catheter.