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Background: : The rhythm-monitoring strategy after catheter ablation (CA) for atrial fibrillation (AF) impacts the detection of atrial arrhythmia recurrence and is not well characterized. We performed a systematic review and meta-regression analysis to determine whether the duration and mode of rhythm monitoring after CA affects detection of atrial arrhythmia recurrence., Methods: Databases were systematically searched for randomized controlled trials of adult patients undergoing first CA for AF from 2007 to 2021. Duration and strategy of rhythm monitoring were extracted. Meta-regression was used to identify any association between duration of monitoring and detection of atrial arrhythmia recurrence. The primary measure of outcome was single-procedure recurrence of atrial arrhythmia., Results: The search strategy yielded 57 trial arms from 56 randomized controlled trials comprising 5322 patients: 36 arms of patients with paroxysmal AF (PAF), and 21 arms of patients with persistent AF (PeAF) or both PAF/PeAF. Intermittent monitoring was associated with detection of significantly less atrial arrhythmia recurrence than continuous monitoring in PAF arms (31.2% vs 46.9%, P  = 0.001), but not in PeAF/PAF-PeAF combined arms (43.3% vs 63.6%, P  = 0.12). No significant relationship was seen between the duration of intermittent rhythm monitoring and atrial arrhythmia recurrence detection in either the PAF ( P  = 0.93) or PeAF/PAF-PeAF combined arms ( P  = 0.20)., Conclusions: Continuous rhythm monitoring detected higher atrial arrhythmia recurrence rates, compared to intermittent rhythm monitoring, in patients with PAF. The duration of intermittent monitoring did not show a statistically significant relationship to the yield of arrhythmia detection, in near identical cohorts of trial subjects undergoing similar interventions, with clinical and research implications., (© 2022 The Authors.)

Background: Multiple studies have examined the prevalence of left atrial appendage thrombus (LAAT) in patients anticoagulated with direct oral anticoagulants (DOACs) and have reported conflicting results., Methods: Studies reporting the prevalence of LAAT on transesophageal echocardiography (TEE) after 3 or more weeks of DOAC therapy were identified. The proportions of anticoagulated patients diagnosed with LAAT were pooled using random-effects models. Prespecified subgroup analyses by the indication of TEE (pre-atrial fibrillation [AF] ablation vs cardioversion) and TEE strategy (routine use vs selective) were conducted via stratification., Results: Forty studies were identified: 22 full manuscripts and 18 abstracts. Only 11 studies performed TEE routinely. Most studies included patients with paroxysmal AF and low thromboembolic risk. The pooled prevalence of LAAT was 2.5% (95% confidence interval [1.6%-3.4%]). The prevalence of LAAT is lower in the pre-AF ablation group compared with pre-cardioversion (1.1% vs 4.0%, P  = 0.033). Routine TEE strategy yielded a lower LAAT prevalence in both groups (0.1% vs 2.3%, P  = 0.002 and 3.2% vs 5.8%, P  = 0.432, respectively)., Conclusion: The reported prevalence of LAAT on TEE in patients treated with DOACs is highly variable. Factors associated with a high LAAT prevalence were pre-cardioversion indication and selective TEE strategy. Routine use of TEE before AF ablation may not be warranted., (© 2020 Canadian Cardiovascular Society. Published by Elsevier Inc.)

Background: High-power short-duration (HPSD) ablation has been explored for pulmonary vein isolation. Early data suggest similar efficacy with shorter procedure times and perhaps greater safety. Data are lacking on the use of this ablation strategy for other arrhythmias., Objective: The purpose of this study was to evaluate the safety, efficacy, and clinical outcomes of HPSD ablation in patients with typical atrial flutter compared to those undergoing ablation with conventional settings., Methods: Consecutive patients undergoing cavotricuspid isthmus (CTI) ablation using standard power settings were compared to those performed after transitioning to HPSD ablation. Demographics, procedural details, and ablation outcomes were prospectively collected. The primary endpoint was duration of radiofrequency energy delivery. Secondary endpoints were radiation duration and analgesia requirements., Results: A total of 114 consecutive subjects undergoing CTI ablation (57 standard power, 57 HPSD) were included. HPSD ablation and electroanatomic mapping/contact force (EAM/CF) use were associated with 66% (95% confidence interval [CI] 58%-73%) and 50% (95% CI 37%-60%) shorter ablation times compared to standard power and not using EAM/CF, respectively. Patients in the HPSD group required 50 mcg less fentanyl relative to the standard ablation arm after adjusting for sex, age, and comorbidities ( P = .048). At a median follow-up of 6 months, 4 patients (7%) in the standard arm had recurrence of atrial flutter, compared to none in HPSD group ( P = .057)., Conclusion: HPSD is a safe and effective approach to CTI ablation. This strategy may reduce ablation time and analgesia requirements. Larger studies and longer follow-up are needed to further evaluate this strategy., (© 2020 Heart Rhythm Society. Published by Elsevier Inc.)

Objectives: This study sought to examine outcomes of our approach to managing a large cohort of patients with Sprint Fidelis (Medtronic, Minneapolis, Minnesota) leads., Background: The optimal management approach for patients with leads under advisory is unknown. Concerns regarding the risk of device infection and complications associated with delaying lead extraction have recently been suggested to argue against abandoning leads under advisory., Methods: All patients with a Sprint Fidelis lead implanted at our institute were included. Lead management options were discussed with patients who presented for device surgery at the time of device upgrade, lead fracture, or elective replacement indicator. Implantation of a new lead with abandonment of the Sprint Fidelis lead was the recommended strategy. Patients were subsequently followed at the device clinic at 6-month intervals and were enrolled prospectively in a longitudinal registry., Results: A total of 520 patients had Sprint Fidelis leads implanted between December 2003 and October 2007 at the study center; 217 patients underwent lead replacement (213 underwent a lead abandonment strategy and 4 underwent a lead extraction strategy). Mean follow-up after lead replacement was 55 ± 33 months. In patients undergoing lead abandonment, 10 of 213 (4.7%) had a procedural complication and 3 of 213 (1.4%) developed subsequent device infection requiring system extraction., Conclusions: In patients with a Sprint Fidelis lead, implanting a new lead without prophylactic extraction may be a feasible and safe strategy but requires longer follow-up., (Copyright © 2019 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Aims: Electrical cardioversion is commonly performed to restore sinus rhythm in patients with atrial fibrillation (AF), but it is unsuccessful in 10-12% of attempts. We sought to evaluate the effectiveness and safety of a novel cardioversion protocol for this arrhythmia., Methods and Results: Consecutive elective cardioversion attempts for AF between October 2012 and July 2017 at a tertiary cardiovascular centre before (Phase I) and after (Phase II) implementing the Ottawa AF cardioversion protocol (OAFCP) as an institutional initiative in July 2015 were evaluated. The primary outcome was cardioversion success, defined as ≥2 consecutive sinus beats or atrial-paced beats in patients with implanted cardiac devices. Secondary outcomes were first shock success, sustained success (sinus or atrial-paced rhythm on 12-lead electrocardiogram prior to discharge from hospital), and procedural complications. Cardioversion was successful in 459/500 (91.8%) in Phase I compared with 386/389 (99.2%) in Phase II (P < 0.001). This improvement persisted after adjusting for age, body mass index, amiodarone use, and transthoracic impedance using modified Poisson regression [adjusted relative risk 1.08, 95% confidence interval (CI) 1.05-1.11; P < 0.001] and when analysed as an interrupted time series (change in level +9.5%, 95% CI 6.8-12.1%; P < 0.001). The OAFCP was also associated with greater first shock success (88.4% vs. 79.2%; P < 0.001) and sustained success (91.6% vs 84.7%; P=0.002). No serious complications occurred., Conclusion: Implementing the OAFCP was associated with a 7.4% absolute increase in cardioversion success and increases in first shock and sustained success without serious procedural complications. Its use could safely improve cardioversion success in patients with AF., Clinical Trial Number: www.clinicaltrials.gov ID: NCT02192957., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.)

Aims: There is ongoing controversy about the need for routine transoesophageal echocardiography (TOE) prior to atrial fibrillation (AF) ablation. Recently, the debate was reignited by the publication of a large series of patients showing a prevalence of left atrial appendage thrombus (LAAT) on TOE of 4.4%. We sought to assess the prevalence of LAAT on TOE before AF ablation at our institution., Methods and Results: Consecutive patients scheduled for AF ablation at our institution between January 2009 and December 2016 were included. All patients were on oral anticoagulation for at least 4 weeks prior to TOE. Transoesophageal echocardiographies were performed 3-5 days prior to scheduled AF ablation. Data were collected utilizing a prospective database. In all, 668 patients and 943 AF ablation procedures were included. Mean age was 64 ± 11 years, 72% were male, average CHADS2 score was 1.0 ± 1.0, and 72% of the patients had paroxysmal AF. At the time of ablation, 496 (53%) were on non-vitamin K antagonist oral anticoagulants (NOACs) and 447 (47%) were on Warfarin. There were three cases with LAAT (3/943, 0.3%), all of whom had persistent AF and were on Warfarin. Two patients underwent surgical ablation and the third patient did not undergo ablation., Conclusion: In our experience, the prevalence of LAAT in patients on anticoagulation therapy undergoing TOE before catheter ablation of AF is 0.3%, which was much lower than recently reported. None of the patients with paroxysmal AF or on NOACs were found to have LAAT. Rather than routine use of TOE prior to AF ablation, a risk-based approach should be considered.

Objectives: This study systematically reviewed the prevalence of pulmonary vein (PV) reconnection in subjects with and without AF recurrence and assessed the relationship between PV reconnection and freedom from atrial fibrillation (AF)., Background: Pulmonary vein reconnection is frequently observed in patients experiencing recurrent AF post catheter ablation. However, its prevalence in AF-free patients has not been well studied., Methods: An electronic search was performed for studies describing PV electrical conduction in subjects with and without AF recurrence post PV isolation (PVI)., Results: Eleven of 5,665 articles met selection criteria. A total of 683 subjects were included in the meta-analysis; 379 had AF recurrence, and 304 were AF-free. Among patients with AF recurrence, 324 of 379 patients (85.5%) had at least 1 pulmonary vein reconnected. Among AF-free patients, 178 of 304 patients (58.6%) had at least 1 PV electrically reconnected, and 126 of 304 (41.4%) had durable PVI. The relative risk (RR) of recurrent AF was significantly lower with durable PVI than with PV reconnection (RR: 0.57; 95% confidence interval [CI]: 0.37 to 0.86; p = 0.008). Analysis of 7 studies including exclusively paroxysmal AF patients (n = 470) showed RR of 0.69 (95% CI: 0.45 to 1.05; p = 0.09)., Conclusions: This meta-analysis shows that durable PVI is associated with a lower risk of AF recurrence after catheter ablation. However, the association was modest, and PV electrical reconnection is common, affecting 58% of AF-free patients. Analysis of studies that included exclusively patients with paroxysmal AF showed a weaker relationship. Additional research is warranted to better understand the mechanism(s) of benefit of catheter ablation for AF and investigate whether PVI should be the primary goal., (Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Cholinesterase inhibitors are used to treat the symptoms of dementia and can theoretically cause bradycardia. Previous studies suggest that patients taking these medications have an increased risk of undergoing pacemaker insertion. Since these drugs have a marginal impact on patient outcomes, it might be preferable to change drug treatment rather than implant a pacemaker. This population-based study determined the association of people with dementia exposed to cholinesterase inhibitor medication and pacemaker insertion., Methods: We used data from the Ontario health administrative databases from January 1, 1993 to June 30, 2012. We included all community-dwelling seniors who had a code for dementia and were exposed to cholinesterase inhibitors (donezepil, galantamine, and rivastigmine) and/or drugs used to treat co-morbidities of hypertension, diabetes, depression and hypothyroidism. We controlled for exposure to anti-arrhythmic drugs. Observation started at first exposure to any medication and continued until the earliest of pacemaker insertion, death, or end of study., Results: 2,353,909 people were included with 96,000 (4.1%) undergoing pacemaker insertion during the observation period. Case-control analysis showed that pacemaker patients were less likely to be coded with dementia (unadjusted OR 0.42 [95%CI 0.41-0.42]) or exposed to cholinesterase inhibitors (unadjusted OR 0.39 [95%CI 0.37-0.41]). That Cohort analysis showed patients with dementia taking cholinesterase inhibitors had a decreased risk of pacemaker insertion (unadj-HR 0.58 [0.55-0.61]). Adjustment for patient age, sex, and other medications did not notably change results, as did restricting the analysis to incident users., Conclusions: Patients taking cholinesterase inhibitors rarely undergo, and have a significantly reduced risk of, cardiac pacemaker insertion.

Introduction: Persistent left superior vena cava (PLSVC) is a rare congenital anomaly of the superior venous system that may be discovered at the time of cardiac implantable electronic device (CIED) implantation., Methods and Results: We present a subject who needed cardiac resynchronization therapy (CRT)-CIED implantation and was discovered to have PLSVC with absent innominate vein during the implant procedure. We were able to successfully implant a CRT-CIED using a right-sided approach via the right superior vena cava (SVC). We present a description of our implant technique and a brief review of the different aspects of CIED implantation in subjects with variants of PLSVC., Conclusion: Superior venous anomalies such as PLSVC can make CIED implantation technically challenging. However, with increasing operator experience, cardiac imaging and appropriate tools successful CIED implantation is possible in almost all cases.

Atrial fibrillation (AF) is the most prevalent arrhythmia and its incidence is on the rise. AF causes significant morbidity and mortality leading to rising AF-related health care costs. There is experimental and clinical evidence from animal and human studies that suggests a role for the renin angiotensin system (RAS) in the etiopathogenesis of AF. This review appraises the current understanding of RAS antagonism, using angiotensin converting enzyme inhibitors (ACE-I), angiotensin receptor blockers (ARB) and aldosterone antagonists (AA), for prevention of AF. RAS antagonism has proven to be effective for primary and secondary prevention of AF in subjects with heart failure and left ventricular (LV) dysfunction.However, most of the evidence for the protective effect of RAS antagonism is from clinical trials that had AF as a secondary outcome or from unspecified post-hoc analyses. The evidence for prevention in subjects without heart failure and with normal LV function is not as clear. RAS antagonism, in the absence of concomitant antiarrhythmic therapy, was not shown to reduce post cardioversion AF recurrences. RAS antagonism in subjects undergoing catheter ablation has also been ineffective in preventing AF recurrences.

Atrial Fibrillation is the most common sustained cardiac arrhythmia worldwide harming millions of people every year. Atrial Fibrillation (AF) abruptly induces rapid conduction between atrial myocytes which is associated with oxidative stress and abnormal calcium handling. Unfortunately this new equilibrium promotes perpetuation of the arrhythmia. Recently, in addition to being the major source of oxidative stress within cells, mitochondria have been observed to fuse, forming mitochondrial networks and attach to intracellular calcium stores in response to cellular stress. We sought to identify a potential role for rapid stimulation, oxidative stress and mitochondrial hyperfusion in acute changes to myocyte calcium handling. In addition we hoped to link altered calcium handling to increased sarcoplasmic reticulum (SR)-mitochondrial contacts, the so-called mitochondrial associated membrane (MAM). We selected the C2C12 murine myotube model as it has previously been successfully used to investigate mitochondrial dynamics and has a myofibrillar system similar to atrial myocytes. We observed that rapid stimulation of C2C12 cells resulted in mitochondrial hyperfusion and increased mitochondrial colocalisation with calcium stores. Inhibition of mitochondrial fission by transfection of mutant DRP1K38E resulted in similar effects on mitochondrial fusion, SR colocalisation and altered calcium handling. Interestingly the effects of 'forced fusion' were reversed by co-incubation with the reducing agent N-Acetyl cysteine (NAC). Subsequently we demonstrated that oxidative stress resulted in similar reversible increases in mitochondrial fusion, SR-colocalisation and altered calcium handling. Finally, we believe we have identified that myocyte calcium handling is reliant on baseline levels of reactive oxygen species as co-incubation with NAC both reversed and retarded myocyte response to caffeine induced calcium release and re-uptake. Based on these results we conclude that the coordinate regulation of mitochondrial fusion and MAM contacts may form a point source for stress-induced arrhythmogenesis. We believe that the MAM merits further investigation as a therapeutic target in AF-induced remodelling.

Aims: An increasing number of transseptal punctures (TSPs) are performed worldwide for atrial ablations. Transseptal punctures can be complex and can be associated with potentially life threatening complications. The purpose of the study was to evaluate the safety and efficacy of a novel transseptal guidewire (TSGW) designed to facilitate TSPs., Methods and Results: Transseptal punctures were performed using a SafeSept TSGW passed through a standard TSP apparatus. Transseptal punctures were performed by standard technique with additional use of a TSGW allowing probing of the interatrial septum without needle exposure and penetration of the fossa into the left atrium (LA). Transseptal puncture using the TSGW was performed in 210 patients. Left atrial access was achieved successfully in 205 of 210 patients (97.6%) and in 96.3% of patients undergoing repeat TSP. Left atrial access was achieved with the first pass in 81.2% (mean 1.4 ± 0.9 passes, range 1-6) using the TSGW. No serious complications were attributable to the use of the TSGW, even in cases of failed TSP., Conclusions: The TSGW is associated with a high success rate for TSP and may be a useful alternative to transoesophageal or intracardiac echocardiogram-guided TSP.

Objectives: We aimed to develop diagnostic criteria for the short QT syndrome (SQTS) to facilitate clinical evaluation of suspected cases., Background: The SQTS is a cardiac channelopathy associated with atrial fibrillation and sudden cardiac death. Ten years after its original description, a consensus regarding an appropriate QT interval cutoff and specific diagnostic criteria have yet to be established., Methods: The MEDLINE database was searched for all reported cases of SQTS in the English language, and all relevant data were extracted. The distribution of QT intervals and electrocardiographic (ECG) features in affected cases were analyzed and compared to data derived from ECG analysis from general population studies., Results: A total of 61 reported cases of SQTS were identified. Index events, including sudden cardiac death, aborted cardiac arrest, syncope, and/or atrial fibrillation occurred in 35 of 61 (57.4%) cases. The cohort was predominantly male (75.4%) and had a mean QT(c) value of 306.7 ms with values ranging from 248 to 381 ms in symptomatic cases. In reference to the ECG characteristics of the general population, and in consideration of clinical presentation, family history, and genetic findings, a highly sensitive diagnostic scoring system was developed., Conclusions: Based on a comprehensive review of 61 reported cases of the SQTS, formal diagnostic criteria have been proposed that will facilitate diagnostic evaluation in suspected cases of SQTS. Diagnostic criteria may lead to a greater recognition of this condition and provoke screening of at-risk family members., (Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Short QT syndrome (SQTS) is a rare genetic disease with a risk of sudden cardiac death. The present report describes syncope in a young man that resulted in a motor vehicle accident. An electrocardiogram and initial investigations were unremarkable, but treadmill testing showed a lack of adaptation of the QT interval, which has been described in SQTS. To evaluate the possible diagnosis of SQTS, DNA sequencing of genes known to be associated with SQTS was performed and identified a novel mutation in the KCNH2 gene. Consequently, the patient was diagnosed with SQTS and the recommendation of implantable cardioverter defibrillator implantation was accepted by the patient before discharge from the hospital.