Catheter ablation for atrial fibrillation has emerged as a main stay for management of atrial fibrillation. It has been shown to be clinically effective and cost effective in multiple trials .

Catheter Ablation of Ventricular Arrhythmias in patients with Prior Mitral Valve Surgery: Challenging, but Feasible and Effective!Amrish Deshmukh, MD; Frank Bogun, MD; Jackson J. Liang, DOElectrophysiology Section, Division of Cardiology; University of Michigan, Ann Arbor, MIFunding: NoneDisclosures: None

Another recent evidence of the clinical utility of the high-power, short-duration radiofrequency ablation strategyKoichiro Ejima, MD, PhD,1, 2 Kyoichiro Yazaki, MD,1 Morio Shoda, MD, PhD, 1, 2Nobuhisa Hagiwara, MD, PhD 11. Department of Cardiology, Tokyo Women’s Medical University2. Clinical Research Division for Heart Rhythm Management, Department of Cardiology, Tokyo Women’s Medical UniversityDepartment of Cardiology, Tokyo Women’s Medical University, Tokyo, Japan8-1, Kawada-cho, Shinjuku-ku, Tokyo, 162-8666 JapanFunding : (None)Disclosures : (None)Corresponding author : Koichiro EjimaE-mail address : [email protected] of Cardiology, Tokyo Women’s Medical University, Tokyo, Japan8-1, Kawada-cho, Shinjuku-ku, Tokyo, 162-8666 JapanTel : +81-3-3353-8111 FAX : +81-3-3356-0441Winkle et al. reviewed the literature of the high-power, short-duration (HPSD) radiofrequency ablation strategy.1We appreciate that they included our study that compared an HPSD ablation with a low-power, long-duration (LPLD) ablation using unipolar signal modification (USM) as a local endpoint during atrial fibrillation (AF) ablation.2 This study included 32 patients (paroxysmal 22, persistent 10) who underwent AF ablation using the HPSD strategy and 32 using the LPLD, and the median follow-up period was 10 months. After that, we reported another study that compared the HPSD ablation with the LPLD ablation using the USM as a local endpoint during AF ablation, which included only patients with paroxysmal AF.3 The number of patients included in the study was larger (HPSD 60, LPLD 60), and the follow-up duration was longer (mean follow-up period of the HPSD group, 12.5 months) than that in our former study. In this study, the freedom from recurrence after a single ablation procedure without any antiarrhythmic drugs was higher in the HPSD group than LPLD group (88.3% vs. 73.3% at 12-months after the procedure, log-rank; P=0.0423). This article was electrically published on May 15, 2020, more than 6 months before Winkle’s review article was received by the editorial office of the Journal of Cardiovascular Electrophysiology (December 4, 2020).We believe that this study is also worth being included the Winkle’s review article and might contribute to future investigators.

Please let me know if it is necessary…we are working on a reply to a previous work

A 27-year-old female presenting palpitation without ECG documentation underwent electrophysiology study. EP study revealed atrioventricular accessory pathway with poor and unidirectional pathway conduction, and a fasciculoventricular pathway. During isoproterenol infusion, delta wave promptly became prominent, after which an antidromic AV reentrant tachycardia was induced. When the pathway was mapped, widely split double pathway potentials were observed at 12 o'clock site of tricuspid annulus during mild preexcitation, demonstrating an example of intra-pathway conduction delay, which can be reversed by isoproterenol. Ablation at the site caused accelerated pathway rhythm and eliminated the pathway, rendering the tachycardia non-inducible.

High Defibrillation Threshold: Brace For Impact Karam Ayoub, MD 1; Travis Richardson , MD11. Division of Cardiac Electrophysiology, Vanderbilt University Medical Center, Nashville, TN, USA.Disclosures : Dr. Richardson has received research funding from Medtronic Inc. and served as a consultant for Philips Inc. and Biosense-Webster Inc.Conflict of interest : noneFunding : noneKey words : Defibrillator , Mortality, Defibrillation Threshold, Sudden Cardiac DeathTotal word count: 1168

Background: Thromboembolism-associated stroke is the most feared complication of Atrial fibrillation (AF). Percutaneous left atrial appendage closure (pLAAC) is indicated for stroke prevention in patients with AF who can’t tolerate long-term anticoagulation. We aim to study gender differences in peri-procedural and readmissions outcomes in pLAAC patients. Methods: Using the national readmission database from January 2016 to December 2018, AF patients undergoing the pLAAC procedure were identified. We used multivariate logistic regression analyses and time-to-event Cox regression analyses to conduct the study. Propensity matching with the Greedy method was done for the accuracy of results. Result: 28,819 patients were included in our study. Among them 11,946 (41.5%) were women and 16,873 (58.6%) were men. The mean age of overall population was 76.1 ± 8.5 years, with women ~ 1 year older than men. The overall rate of complications was higher in women (8.6% vs 6.6%, P<0.001), primarily driven by bleeding-related complications i.e., Major bleed (OR: 1.32 95% CI: 1.03-1.69, p=0.029), blood transfusion (OR: 1.45, 95% CI: 1.06-1.97, p=0.019) and cardiac tamponade (OR: 1.80, 95% CI: 1.13-2.89, p=0.014). Women had two times higher peri-procedural ischemic stroke. There was no difference in peri-procedural mortality. Women remained at 20% and 13% higher risk for readmission at 30 days and 6 months of discharge. Conclusion: Women had higher peri-procedural complications and were at higher risk of readmissions at 30 days and six months. However, there was no difference in mortality during the index hospitalization. Further studies are necessary to determine causality.

Aims: The MicraTM transcatheter pacing system (TPS) (Medtronic) is the only leadless pacemaker that promotes atrioventricular (AV) synchrony via accelerometer-based atrial sensing. Data regarding the real-world experience with this novel system are currently lacking. We sought to characterize patients undergoing MicraTM -AV implants, describe percentage AV synchrony achieved, and analyze the causes for suboptimal AV synchrony. Methods: In this retrospective cohort study, electronic medical records from 56 consecutive patients undergoing MicraTM -AV implants at the Mayo Clinic sites in Minnesota, Florida, and Arizona with a minimum follow-up of 3 months were reviewed. Demographic data, comorbidities, echocardiographic data, and clinical outcomes were compared among patients with and without atrial synchronous-ventricular pacing (AsVP) ≥70%. Results: Fifty-six percent of patients achieved AsVP ≥70%. Patients with adequate AsVP had smaller body mass indices, a lower proportion of congestive heart failure and pulmonary hypertension. Echocardiographic parameters and procedural characteristics were similar across the two groups. Active device troubleshooting was associated with higher AsVP. The likely reasons for low AsVP were persistent atrial arrhythmias, small A4-wave amplitude, and inadequate device reprogramming. Importantly, in patients with low AsVP, subjective clinical worsening was not noted during follow-up. Conclusion: With the increasing popularity of leadless PM, it is paramount for device implanting teams to be familiar with common predictors of AV synchrony and troubleshooting with MicraTM -AV devices.

Introduction: Bradyarrhythmias are an established red flag for storage cardiac conditions including Anderson-Fabry disease (AFD). The prevalence of bradyarrhythmias requiring a pacemaker (PM) and their timing in AFD is unresolved. We evaluated prevalence and predictors of PM requirement in a large AFD cohort, investigating the occurrence of bradyarrhythmias as initial versus late manifestation. Methods: we retrospectively evaluated 82 consecutive AFD patients referred to our multidisciplinary referral centre from 1994 to 2020 with a median follow up of 6.9 years, identifying those requiring pacing. Univariable analysis was performed to identify cardiac features associated with PM implantantion. Results: Five of 82 (6%) AFD patients required PM implantation (5/39, i.e. 13% of those with cardiac involvement), always in the context of advanced cardiomyopathy. In none, bradyarrhythmias were the presenting feature. Indications included sick sinus syndrome in 3 patients, advanced atrio-ventricular block in 2 patients. QRS prolongation during follow up strongly correlated with the onset of bradyarrhythmias. Conclusions: Severe bradyarrhythmias are relatively frequent in patients with AFD cardiomyopathy, but do not represent a mode of presentation, occurring late in the disease course and always in the context of advanced cardiac involvement. Monitoring QRS variations over time may help to identify patients requiring pacing.

Objective: To explore the safety and feasibility of left bundle branch area pacing (LBBAP) in children. Methods: This study observed 12 children attempted LBBAP from 2019 to 2021 in our department prospectively. Clinical data, pacing parameters, electrocardiograms, echocardiographic measurements and complications were recorded at implant and during follow-up. Results: The 12 patients aged between 3 and 14ys and weighted from 13 to 48kg. 11 patients were diagnosed with third-degree AVB and 1 patient (case 4) suffered from cardiac dysfunction due to right ventricular apical pacing (RVAP). LBBAP was successfully achieved in all patients with narrow QRS complexes. LVEF of case 4 recovered on the 3rd day after LBBAP. The median of LVEDD Z score of the 12 patients decreased from 1.75 to1.05 3 months after implantation (p<0.05). The median of paced QRS duration was 103ms. The median of pacing threshold, R-wave amplitude and impedance were 0.85V, 15mV and 717Ω respectively and remained stable during follow-up. No complications such as loss of capture, lead dislodgement or septal perforation occurred. Conclusions: LBBAP can be performed safely in children with narrow QRS duration and stable pacing parameters. Cardiac dysfunction caused by long-term RVAP can be corrected by LBBAP quickly.

The classification of AVNRT is based on HA and VA interval. Typical AVNRT is diagnosed in presence of HA ≤70 ms OR VA interval ≤60 ms and HA>70ms or VA >60ms is required to diagnose atypical AVNRT. This might be fallacious in some clinical situations. The septal VA and the “shortest” VA may be also different depending on clinical scenario .

Cutting through the Fat: Relationship Between Comorbidities and Arrhythmias in Hypertrophic Cardiomyopathy Alan Sugrue MBBCh, MSc; David Lin MD, FHRSCardiovascular Division, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PAManuscript word count: 1223Conflicts of interest: noneFunding: noneAddress for Correspondence:David Lin, MDHospital of the University of Pennsylvania3400 Spruce Street9 Founders PavilionPhiladelphia, PA 19104Email: [email protected]

Ventricular outflow is a common site for idiopathic PVCs and repetitive ventricular arrhythmias. Sites of origin of these arrhythmias may vary from the sites of earliest activation mapped. Better definition of the site of origin can help avoid unnecessary large volume ablation to suppress these arrhythmia.

Epicardial surgical clip is showed to be a safe and effective tool in order to achieve a complete left atrial appendage (LAA) exclusion thus reducing the risk of stroke in patients with atrial fibrillation. Historically, other methods as surgical ligation, internal oversewing or external stapling showed to be largely uneffective with an incidence of LAA residual flow ranging from 25% to 35% thus, increasing per se 5- to 10-fold the risk of stroke. Epicardial LAA exclusion by means of external clip could be potentially released under transesophageal echocardiographic guidance thus increasing the procedural success rate of complete closure with no residual stump left.

Background Magnetic Resonance imaging (MRI) in patients (pts) with MRI-conditional cardiovascular implantable electronic devices (CIED) remain a logistical issue for device programming during the scan. In current practice, a trained person needs to be present on-site to program CIED for MRI scan. This can cause delay in patient care, rescheduling of tests and increase healthcare costs. A novel remote programming (RP) strategy can be utilized to reprogram the CIED remotely. We sought to explore the feasibility and safety of RP of CIED’s in pts undergoing MRI scan. Methods We implemented the Medtronic CIED RP software at our institution after ensuring HIPAA compliance. The MRI technician started the session by contacting an off-site remote operator and placing a programmer wand from 2090 Medtronic programmer over CIED. The remote operator logged into a remote access software and provided a unique access code to the MRI technician. After entering the access code into the programmer, the remote operator was able to program the device as needed. We conducted a periodic audit of the first 209 pts who underwent RP of CIED’s for MRI. Outcomes analyzed were safety parameters during RP. Results Of the 209 MRI scans, 51 scans were performed urgently. There were no connectivity and programming problems or need for MRI rescheduling. In-person reprogramming was not required for any pt. All scans were completed safely in a timely manner, and there were no reports of CIED malfunction. Conclusions Remote programming of CIED’s for MRI scans is a safe and effective strategy.

Background: As pediatric implantable cardioverter defibrillator (ICD) utilization increases, hospital admission rates will increase. Data regarding hospitalizations among pediatric patients with ICDs is lacking. In addition, hospital mortality rates are unknown. This study aimed to evaluate 1) trends in hospitalization rates of admissions over 20 years, 2) hospital mortality, and 3) factors associated with hospital mortality among pediatric admissions with ICDs. Methods: The Kids’ Inpatient Database (2000-2016) was used to identify all hospitalizations with an existing ICD 20 years of age. ICD9/10 codes were used to stratify admissions by underlying diagnostic category as: 1) congenital heart disease (CHD), 2) primary arrhythmia, 3) primary cardiomyopathy, or 4) other. Trends were analyzed using linear regression. Hospital and patient characteristics among hospital deaths were compared to those surviving to discharge using mixed multivariable logistic regression, accounting for hospital clustering. Results: Of 42,570,716 hospitalizations, 4165 were admitted <21 years with an ICD. ICD admissions increased four-fold (p = 0.002) between 2000-2016. Hospital death occurred in 54 (1.3%). In multivariable analysis, cardiomyopathy (OR 3.5, 95%CI 1.1–11.2, p=0.04) and CHD (OR 4.8, 95%CI 1.5–15.6, p=0.01) were significantly associated with mortality. In further exploratory multivariable analysis incorporating a coexisting diagnosis of heart failure, only the presence of heart failure remained associated with mortality (OR 8.6, 95%CI 3.7-20.0, p<0.0001). Conclusions: Pediatric ICD hospitalization are increasing over time and hospital mortality is low (1.3%). Hospital mortality is associated with cardiomyopathy or CHD; however, the underlying driver for in-hospital death may be heart failure.

A left bundle branch block morphology tachycardia with fragmented potentials at the His bundle area Masahiro Toba, MDa, Toshihiro Nasu, CEb, Nobuyoshi Nekomiya, CEb, Ryo Itasaka, CEb, Takao Makino, MDa, Hisashi Yokoshiki, MD, PhDaaDepartment of Cardiovascular Medicine, Sapporo City General Hospital, Sapporo, JapanbDivision of Medical Engineering Center, Sapporo City General Hospital, Sapporo, JapanAddress for correspondence :Hisashi Yokoshiki MD, PhDE-mail:[email protected] of Cardiovascular Medicine Sapporo City General Hospital, Kita-11, Nishi-13, Chuo-ku, Sapporo 060-8604, Japan.Phone: 81-11-726-2211Fax: 81-11-726-7912Key words : longitudinal dissociated his bundle, left bundle branch block morphology tachycardia, fragmented potentials, radiofrequency ablation

Background: Cryoballoon (CB) based pulmonary vein isolation (PVI) has proven to be as effective as radiofrequency (RF) based ablation. Different ablation protocols took the individual time-to-isolation (TTI) into account aiming at shorter but equally or even more effective freeze-cycles. The current study sought to assess the impact of the TTI on PVI durability in patients undergoing a repeat procedure for recurrence of atrial tachyarrhythmia (ATA). Methods and Results: In 205 patients with ATA recurrence after previous CB-based PVI a total of 806 PVs were identified. One hundred-twenty-six out of 806 PVs (16%) were previously treated with a TTI guided ablation (protocol #1; TTI+120 sec.), in 92/806 (11%) PVs TTI was only monitored (m) but fixed freeze-cycles were applied (protocol #2; mTTI) and in 588/806 (73%) a fixed freeze-cycle was applied without TTI-monitoring. There was no difference in the PV-reconduction rate between the groups (P=0.23). The right inferior pulmonary vein (RIPV) showed overall significantly higher reconduction rates compared to the other PVs (RIPV – left inferior PV (LIPV) p<0.003, -left superior PV (LSPV) p<0.001, - right superior PV RSPV p<0.013). In 21 patients (10%) only for the RIPV reconduction was assessed. Conclusions: TTI based CB ablation did not show significant differences regarding PV-reconduction rates compared to the other protocols.