Percutaneous alternative to the Maze procedure for the treatment of persistent or long-standing persistent atrial fibrillation (aMAZE trial): Rationale and design

2023 Cardiac Society of Australia and New Zealand Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation

Catheter ablation for atrial fibrillation (AF) has increased exponentially in many developed countries, including Australia and New Zealand. This Expert Position Statement on Catheter and Surgical Ablation for Atrial Fibrillation from the Cardiac Society of Australia and New Zealand (CSANZ) recognises healthcare factors, expertise and expenditure relevant to the Australian and New Zealand healthcare environments including considerations of potential implications for First Nations Peoples. The statement is cognisant of international advice but tailored to local conditions and populations, and is intended to be used by electrophysiologists, cardiologists and general physicians across all disciplines caring for patients with AF. They are also intended to provide guidance to healthcare facilities seeking to establish or maintain catheter ablation for AF.

Pulmonary Vein Isolation With or Without Left Atrial Appendage Ligation in Atrial Fibrillation: The aMAZE Randomized Clinical Trial

Importance

Left atrial appendage elimination may improve catheter ablation outcomes for atrial fibrillation.

Objective

To assess the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to catheter pulmonary vein isolation for nonparoxysmal atrial fibrillation.

Design, Setting, and Participants

This multicenter, prospective, open-label, randomized clinical trial evaluated the safety and effectiveness of percutaneous left atrial appendage ligation adjunctive to planned pulmonary vein isolation for nonparoxysmal atrial fibrillation present for less than 3 years. Eligible patients were randomized in a 2:1 ratio to undergo left atrial appendage ligation and pulmonary vein isolation or pulmonary vein isolation alone. Use of a 2:1 randomization ratio was intended to provide more device experience and safety data. Patients were enrolled from October 2015 to December 2019 at 53 US sites, with the final follow-up visit on April 21, 2021.

Interventions

Left atrial appendage ligation plus pulmonary vein isolation compared with pulmonary vein isolation alone.

Main Outcomes and Measures

A bayesian adaptive analysis was used for primary end points. Primary effectiveness was freedom from documented atrial arrythmias of greater than 30 seconds duration 12 months after undergoing pulmonary vein isolation. Rhythm was assessed by Holter monitoring at 6 and 12 months after pulmonary vein isolation, symptomatic event monitoring, or any electrocardiographic tracing obtained through 12 months after pulmonary vein isolation. Primary safety was a composite of predefined serious adverse events compared with a prespecified 10% performance goal 30 days after the procedure. Left atrial appendage closure was evaluated through 12 months after pulmonary vein isolation.

Results

Overall, 404 patients were randomized to undergo left atrial appendage ligation plus pulmonary vein isolation and 206 were randomized to undergo pulmonary vein isolation alone. Primary effectiveness was 64.3% with left atrial appendage ligation and pulmonary vein isolation and 59.9% with pulmonary vein isolation only (difference, 4.3% [bayesian 95% credible interval, -4.2% to 13.2%]; posterior superiority probability, 0.835), which did not meet the statistical criterion to establish superiority (0.977). Primary safety was met, with a 30-day serious adverse event rate of 3.4% (bayesian 95% credible interval, 2.0% to 5.0%; posterior probability, 1.0) which was less than the prespecified threshold of 10%. At 12 months after pulmonary vein isolation, complete left atrial appendage closure (0 mm residual communication) was observed in 84% of patients and less than or equal to 5 mm residual communication was observed in 99% of patients.

Conclusions and Relevance

Percutaneous left atrial appendage ligation adjunctive to pulmonary vein isolation did not meet prespecified efficacy criteria for freedom from atrial arrhythmias at 12 months compared with pulmonary vein isolation alone for patients with nonparoxysmal atrial fibrillation, but met prespecified safety criteria and demonstrated high rates of closure at 12 months.

Trial Registration

ClinicalTrials.gov Identifier: NCT02513797.

Catheter ablation for non-paroxysmal atrial fibrillation. A review

Atrial fibrillation (AF), the most common cardiac arrhythmia is associated with increased morbidity and mortality. The higher mortality is due to the risk of heart failure and cardioembolic events. This in-depth review focuses on the strategies and efficacy of catheter ablation for non-paroxysmal atrial fibrillation. The main medical databases were searched for contemporary studies on catheter ablation for non-paroxysmal AF. Catheter ablation is currently proven to be the most effective treatment for AF and consists of pulmonary vein isolation as the cornerstone plus additional ablations. In terms of SR maintenance, it is less effective in non-paroxysmal AF than in paroxysmal patients. but the clinical benefit in non-paroxysmal patients is substantially higher. Since pulmonary vein isolation is ineffective, a variety of techniques have been developed, e.g. linear ablations, ablation of complex atrial fractionated electrograms, etc. Another paradox consists in the technique of catheter ablation. Despite promising results in early observation studies, further randomized studies have not confirmed the initial enthusiasm. Recently, a new approach, pulsed-field ablation, appears promising. This is an in-depth summary of current technologies and techniques for the ablation of non-paroxysmal AF. We discuss the benefits, risks and implications in the treatment of patients with non-paroxysmal AF.

Progress in atrial fibrillation ablation during 25 years of Europace journal

The first edition of Europace journal in 1999 came right around the time of the landmark publication of the electrophysiologists from Bordeaux, establishing how elimination of ectopic activity from the pulmonary veins (PVs) resulted in a marked reduction of atrial fibrillation (AF). The past 25 years have seen an incredible surge in scientific interest to develop new catheters and energy sources to optimize durability and safety of ablation, as well as study the mechanisms for AF and devise ablation strategies. While ablation in the beginning was performed with classic 4 mm tip catheters that emitted radiofrequency (RF) energy to create tissue lesions, this evolved to using irrigation and contact force (CF) measurement while increasing power. Also, so-called single-shot devices were developed with balloons and arrays to create larger contiguous lesions, and energy sources changed from RF current to cryogenic ablation and more recently pulsed field ablation with electrical current. Although PV ablation has remained the basis for every AF ablation, it was soon recognized that this was not enough to cure all patients, especially those with non-paroxysmal AF. Standardized approaches for additional ablation targets have been used but have not been satisfactory in all patients so far. This led to highly technical mapping systems that are meant to unravel the drivers for the maintenance of AF. In the following sections, the development of energies, strategies, and tools is described with a focus on the contribution of Europace to publish the outcomes of studies that were done during the past 25 years.

SCAI/HRS Expert Consensus Statement on Transcatheter Left Atrial Appendage Closure

Exclusion of the left atrial appendage to reduce thromboembolic risk related to atrial fibrillation was first performed surgically in 1949. Over the past 2 decades, the field of transcatheter endovascular left atrial appendage closure (LAAC) has rapidly expanded, with a myriad of devices approved or in clinical development. The number of LAAC procedures performed in the United States and worldwide has increased exponentially since the Food and Drug Administration approval of the WATCHMAN (Boston Scientific) device in 2015. The Society for Cardiovascular Angiography & Interventions (SCAI) has previously published statements in 2015 and 2016 providing societal overview of the technology and institutional and operator requirements for LAAC. Since then, results from several important clinical trials and registries have been published, technical expertise and clinical practice have matured over time, and the device and imaging technologies have evolved. Therefore, SCAI prioritized the development of an updated consensus statement to provide recommendations on contemporary, evidence-based best practices for transcatheter LAAC focusing on endovascular devices.

The Strengths and Weaknesses of Left Atrial Appendage Ligation or Exclusion (LARIAT, AtriaClip, Surgical Suture)

Left atrial appendage (LAA) epicardial exclusion has been associated with addressing 2 potential deleterious consequences attributed to the LAA, namely, thrombus formation and an arrhythmogenic contributor in advanced forms of atrial fibrillation. With more than 60 years of history, the surgical exclusion of the LAA has been firmly established. Numerous approaches have been used for surgical LAA exclusion including surgical resections, suture ligation, cutting and non-cutting staples, and surgical clips. Additionally, a percutaneous epicardial LAA ligation approach has been developed. A discussion of the various epicardial LAA exclusion approaches and their efficacy will be discussed, along with the salient beneficial affects on LAA thrombus formation, LAA electrical isolation and neuroendocrine homeostasis.

Appropriate Use Criteria of Left Atrial Appendage Closure Devices: Latest Evidences

Atrial fibrillation is the most common arrythmia and it is linked to an increased risk of stroke. Even if anticoagulation therapy reduces the rate of stroke the benefits of this therapy have to been balanced with the increased risk of hemorrhagic event. Left atrial appendage closure is a valid alternative to long term anticoagulation in patients with atrial fibrillation and high hemorrhagic risk. Actually new devices with different features have been tested and introduced progressively in the clinical practice. Improvements preprocedural imaging evaluation and the learning curve of the operators led to percutaneous left atrial appendage closure a safe and effective procedure. A good knowledge of different devices and the technique of implant is necessary for optimization percutaneous left atrial appendage closure and the reduction of complications during the acute phase and follow up.

SCAI/HRS expert consensus statement on transcatheter left atrial appendage closure

Exclusion of the left atrial appendage to reduce thromboembolic risk related to atrial fibrillation was first performed surgically in 1949. Over the past 2 decades, the field of transcatheter endovascular left atrial appendage closure (LAAC) has rapidly expanded, with a myriad of devices approved or in clinical development. The number of LAAC procedures performed in the United States and worldwide has increased exponentially since the Food and Drug Administration approval of the WATCHMAN (Boston Scientific) device in 2015. The Society for Cardiovascular Angiography & Interventions (SCAI) has previously published statements in 2015 and 2016 providing societal overview of the technology and institutional and operator requirements for LAAC. Since then, results from several important clinical trials and registries have been published, technical expertise and clinical practice have matured over time, and the device and imaging technologies have evolved. Therefore, SCAI prioritized the development of an updated consensus statement to provide recommendations on contemporary, evidence-based best practices for transcatheter LAAC focusing on endovascular devices.

Atrial fibrillation: Primary prevention, secondary prevention, and prevention of thromboembolic complications: Part 2

Atrial fibrillation (AF), the most common sustained cardiac arrhythmia, once thought to be benign as long as the ventricular rate was controlled, is associated with significant cardiac morbidity and mortality. Increasing life expectancy driven by improved health care and decreased fertility rates has, in most of the world, resulted in the population aged ≥65 years growing more rapidly than the overall population. As the population ages, projections suggest that the burden of AF may increase more than 60% by 2050. Although considerable progress has been made in the treatment and management of AF, primary prevention, secondary prevention, and prevention of thromboembolic complications remain a work in progress. This narrative review was facilitated by a search of MEDLINE to identify peer-reviewed clinical trials, randomized controlled trials, meta-analyses, and other clinically relevant studies. The search was limited to English-language reports published between 1950 and 2021. Atrial fibrillation was searched using the terms primary prevention, hyperthyroidism, Wolff-Parkinson-White syndrome, catheter ablation, surgical ablation, hybrid ablation, stroke prevention, anticoagulation, left atrial occlusion and atrial excision. Google and Google scholar as well as bibliographies of identified articles were reviewed for additional references. In these two manuscripts, we discuss the current strategies available to prevent AF, then compare non-invasive and invasive treatment strategies to diminish AF recurrence. In addition, we examine the pharmacological, percutaneous device and surgical approaches to prevent stroke as well as other types of thromboembolic events.

Low-voltage area substrate modification for atrial fibrillation ablation: a systematic review and meta-analysis of clinical trials

AIMS

The value of additional ablation beyond pulmonary vein isolation for atrial fibrillation (AF) ablation is unclear, especially for persistent AF. The optimal target for substrate modification to improve outcomes is uncertain. We investigate the utility of low-voltage area (LVA) substrate modification in patients undergoing catheter ablation for AF.

METHODS

This meta-analysis was reported according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Medline, Scopus and Cochrane Central Register of Controlled Trials were systematically searched to identify relevant studies. Risk of bias was assessed using the Cochrane risk of bias tool. Only randomized studies were included. AF patients who underwent catheter ablation with voltage-guided substrate modification targeting LVA (LVA group) vs. conventional ablation approaches not targeting LVA (non-LVA group) were compared.

RESULTS

Four studies comprising 539 patients were included (36% female). Freedom from arrhythmia (FFA) in patients with persistent AF was greater in the LVA group [risk ratio (RR) 1.30; 95% confidence interval (CI) 1.03-1.64]. There was no difference in FFA in patients with paroxysmal AF between groups (RR 1.30; 95% CI 0.89-1.91). There was no difference in total procedural time (mean difference -17.54 min; 95% CI -64.37 to 29.28 min) or total ablation time (mean difference -36.17 min; 95% CI -93.69 to 21.35 min) in all included patients regardless of AF type between groups. There was no difference in periprocedural complications between groups in all included patients regardless of AF type (RR 0.93; 95% CI 0.22-3.82).

CONCLUSION

This meta-analysis demonstrates improved FFA in persistent AF patients who underwent voltage-guided substrate modification targeting LVA.

Pulmonary vein isolation alone versus pulmonary vein isolation with additional extensive ablation for paroxysmal and persistent atrial fibrillation

Background

The value of additional ablation beyond pulmonary vein isolation for atrial fibrillation (AF) ablation is unclear, especially for persistent AF. It is uncertain whether substrate modification with additional extensive ablation improves outcomes. We reviewed our experience to determine whether pulmonary vein isolation with additional extensive ablation (PVIEA) improves outcomes compared to pulmonary vein isolation alone (PVIA) for AF ablation.

Methods

Consecutive cases of patients with PVIA versus PVIEA were compared between September 9, 2013 and December 12, 2020. Procedural data collected include radiofrequency ablation delivery time (RADT) and arrhythmia inducibility. Clinical data collected include sinus rhythm maintenance post‐procedure.

Results

A total of 235 patients were studied (67 PVIA and 168 PVIEA). RADT was shorter when comparing ablation with PVIA versus PVIEA (32 vs. 40 min; p = .04). More arrhythmias were inducible with PVIEA (p < .01). There was no difference in sinus rhythm maintenance by Kaplan–Meier survival analysis (log‐rank test p = .75), after 3 or 12 months between groups overall, and when stratified by AF type (paroxysmal and persistent), left atrial volume, CHA₂DS₂‐VASc score, left ventricular ejection fraction, or catheter ablation setting (high‐power short‐duration, standard‐power standard‐duration, temperature‐controlled non‐contact‐force).

Conclusion

AF ablation with PVIA or PVIEA produces similar sinus rhythm maintenance overall and when stratified by catheter setting and AF type. PVIA reduced procedure times and less arrhythmias were inducible post‐ablation.

The Strengths and Weaknesses of Left Atrial Appendage Ligation or Exclusion (LARIAT, AtriaClip, Surgical Suture)

Left atrial appendage (LAA) epicardial exclusion has been associated with addressing 2 potential deleterious consequences attributed to the LAA, namely, thrombus formation and an arrhythmogenic contributor in advanced forms of atrial fibrillation. With more than 60 years of history, the surgical exclusion of the LAA has been firmly established. Numerous approaches have been used for surgical LAA exclusion including surgical resections, suture ligation, cutting and non-cutting staples, and surgical clips. Additionally, a percutaneous epicardial LAA ligation approach has been developed. A discussion of the various epicardial LAA exclusion approaches and their efficacy will be discussed, along with the salient beneficial affects on LAA thrombus formation, LAA electrical isolation and neuroendocrine homeostasis.

Long-Term Stroke Risk in Patients Undergoing Left Atrial Appendage Ablation With and Without Complete Isolation

Background: Catheter ablation (CA) for atrial fibrillation (AF), may require ablation beyond the pulmonary veins. Prior data suggest that additional LA ablation, particularly left atrial appendage (LAA) ablation, may alter atrial function leading to increased risk of ischemic stroke or transient ischemic attack (IS/TIA). We sought to study the long-term risk of IS/TIA in patients receiving ablation at the LAA compared to those receiving PVI alone and those receiving PVI with additional non-LAA locations.

Methods: 350 patients who underwent CA for AF from 2008 to 2018 were included in the study. Locations of ablation in LA evaluated were the posterior wall, anterior wall, inferior wall, inter-atrial septum, lateral wall and the left atrial appendage (LAA). Patients undergoing LAA ablation were further divided as complete isolation (LAAi) and without complete isolation (LAAa).

Results: Mean follow up of 4.8 years. In entire cohort, risk of IS/TIA was 1.62/100 patient-years (pys). The risk was highest in patients with LAAi (3.81/100 pys), followed by ablation LAAa (3.74/100 pys). Amongst all LA locations, only LAAi (HR 3.32, p = 0.03) and LAAa (HR 3.18, p = 0.02) were statistically significant predictors of IS/TIA after adjusting for OAC (Oral anticoagulant) use and baseline CHA₂DS₂VASc score.

Conclusions: During long term follow-up, only ablation at the left atrial appendage with and without complete isolation was independently associated with an increased risk of IS/TIA in patients undergoing CA for AF. Potential strategies to reduce stroke risk, such as LAA closure, should be considered in these patients.

Standalone epicardial left atrial appendage exclusion for thromboembolism prevention in atrial fibrillation

OBJECTIVES

Most strokes associated with atrial fibrillation (AF) result from left atrial appendage thrombi. Oral anticoagulation can reduce stroke risk but is limited by complication risk and non-compliance. Left atrial appendage exclusion (LAAE) is a new surgical option to reduce stroke risk in AF. The study objective was to evaluate the safety and feasibility of standalone thoracoscopic LAAE in high stroke risk AF patients.

METHODS

This was a retrospective, multicentre study of high stroke risk AF patients who had oral anticoagulation contraindications and were not candidates for ablation nor other cardiac surgery. Standalone thoracoscopic LAAE was performed using 3 unilateral ports access and epicardial clip. Periprocedural adverse events, long-term observational clinical outcomes and stroke rate were evaluated.

RESULTS

Procedural success was 99.4% (174/175 patients). Pleural effusion occurred in 4 (2.3%) patients; other periprocedural complications were <1% each. One perioperative haemorrhagic stroke occurred (0.6%). No phrenic nerve palsy or cardiac tamponade occurred. Predicted annual ischaemic stroke rate of 4.8/100 patient-years (based on median CHA2DS2-VASc score of 4.0) was significantly higher than stroke risk observed in follow-up after LAAE. No ischaemic strokes occurred (median follow-up: 12.5 months), resulting in observed rate of 0 (95% CI 0-2.0)/100 patient-years (P < 0.001 versus predicted). Six all-cause (non-device-related) deaths occurred during follow-up.

CONCLUSIONS

Study proved that a new surgical option, standalone thoracoscopic LAAE, is feasible and safe. With this method, long-term stroke rate may be reduced compared to predicted for high-risk AF population.

Atrial Fibrillation and Ischemic Stroke: A Clinical Review

Atrial fibrillation (AF) is an important risk factor for ischemic stroke resulting in a fivefold increased stroke risk and a twofold increased mortality. Our understanding of stroke mechanisms in AF has evolved since the concept of atrial cardiopathy was introduced as an underlying pathological change, with both AF and thromboembolism being common manifestations and outcomes. Despite the strong association with stroke, there is no evidence that screening for AF in asymptomatic patients improves clinical outcomes; however, there is strong evidence that patients with embolic stroke of undetermined source may require long-term monitoring to detect silent or paroxysmal AF. Stroke prevention in patients at risk, assessed by the CHA₂DS₂-VASc score, was traditionally achieved with warfarin; however, direct oral anticoagulants have solidified their role as safe and effective alternatives. Additionally, left atrial appendage exclusion has emerged as a viable option in patients intolerant of anticoagulation. When patients with AF have an acute stroke, the timing of initiation or resumption of anticoagulation for secondary stroke prevention has to be balanced against the risk of hemorrhagic conversion. Multiple randomized clinical trials are currently underway to determine the best timing for administration of anticoagulants following acute ischemic stroke.

The NCDR Left Atrial Appendage Occlusion Registry

BACKGROUND

Left atrial appendage occlusion (LAAO) to prevent stroke in patients with atrial fibrillation has been evaluated in 2 randomized trials; post-approval clinical data are limited.

OBJECTIVES

The purpose of this study was to describe the National Cardiovascular Data Registry (NCDR) LAAO Registry and present patient, hospital, and physician characteristics and in-hospital adverse event rates for Watchman procedures in the United States during its first 3 years.

METHODS

The authors describe the LAAO Registry structure and governance, the outcome adjudication processes, and the data quality and collection processes. They characterize the patient population, performing hospitals, and in-hospital adverse event rates.

RESULTS

A total of 38,158 procedures from 495 hospitals performed by 1,318 physicians in the United States were included between January 2016 and December 2018. The mean patient age was 76.1 ± 8.1 years, the mean CHA₂DS₂-VASc (congestive heart failure, hypertension, 65 years of age and older, diabetes mellitus, previous stroke or transient ischemic attack, vascular disease, 65 to 74 years of age, female) score was 4.6 ± 1.5, and the mean HAS-BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly) score was 3.0 ± 1.1. The median annual number of LAAO procedures performed for hospitals was 30 (interquartile range: 18 to 44) and for physicians was 12 (interquartile range: 8 to 20). Procedures were canceled or aborted in 7% of cases; among cases in which a device was deployed, 98.1% were implanted with <5-mm leak. Major in-hospital adverse events occurred in 2.16% of patients; the most common complications were pericardial effusion requiring intervention (1.39%) and major bleeding (1.25%), whereas stroke (0.17%) and death (0.19%) were rare.

CONCLUSIONS

The LAAO Registry has enrolled >38,000 patients implanted with the device. Patients were generally older with more comorbidities than those enrolled in the pivotal trials; however, major in-hospital adverse event rates were lower than reported in those trials.

Percutaneous epicardial approach for LAA ligation

PURPOSE

The left atrial appendage (LAA) is believed to be a source for thrombus formation and an ancillary structure involved in the initiation and maintenance of atrial fibrillation (AF). LAA ligation has been proposed as adjunctive therapy for the treatment of AF. This study will determine the feasibility of a percutaneous epicardial approach for LAA ligation.

METHODS

The pericardium of 5 dogs was accessed via percutaneous subxyphoid approach. A 20F epicardial cannula was inserted into the pericardial space and contrast-injected to visualize the LAA. Under fluoroscopic guidance, a suction cup catheter was inserted and attached to the LAA. A 12F snare device was inserted over the vacuum cup to ligate the LAA. The closure of the LAA was verified with LA angiography, in the first 2 dogs, and ICE in all 5 animals. All animals were sacrificed for post hoc assessment of LAA closure.

RESULTS

All 5 dogs underwent successful epicardial suture ligation of the LAA. In the first 2 dogs, LA angiography demonstrated complete closure of the LAA. All dogs underwent gross examination of the LAA. Post hoc assessment was notable for a small well-circumscribed hematoma on the LAA, consistent with point of suction cup attachment, as well as complete closure of the entire LAA. No laceration or perforation was noted on the LAA.

CONCLUSIONS

Exclusion of the LAA via a novel percutaneous epicardial-only approach was successful without complications. This demonstrates the feasibility of this technique in an animal model, and may provide an effective approach for epicardial-only LAA exclusion in humans.

Subxiphoid Hybrid Epicardial-Endocardial Atrial Fibrillation Ablation and LAA Ligation: Initial Sub-X Hybrid MAZE Registry Results

OBJECTIVES

The aim of this study was to assess the safety and efficacy of a new subxiphoid hybrid epicardial-endocardial atrial fibrillation (AF) ablation and left atrial appendage (LAA) ligation approach for the treatment of persistent AF.

BACKGROUND

Surgical hybrid ablation procedures have shown promise for maintaining sinus rhythm versus catheter ablation but are associated with increased periprocedural adverse events.

METHODS

Patients with symptomatic persistent AF (n = 33, mean age 64 ± 9 years, 25 men) who had antiarrhythmic drug therapy or prior catheter ablation was unsuccessful were referred for hybrid epicardial-endocardial AF ablation and LAA exclusion. LAA closure was confirmed by transesophageal echocardiographic Doppler flow and/or computed tomographic angiography 1 to 3 months post-ligation. The incidence of atrial tachycardia or AF recurrence, LAA closure, thromboembolic events, and post-operative complications were assessed.

RESULTS

All 33 patients underwent successful LAA ligation with epicardial ablation of the posterior left atrial wall, as well as endocardial pulmonary vein isolation and cavotricuspid isthmus ablation. Freedom from atrial tachycardia or AF was 91% (20 of 22 patients) at 6 months, 90% (18 of 20 patients) at 12 months, 92% (11 of 12 patients) at 18 months, and 92% (11 of 12) at 24 months. There were no acute periprocedural complications (<7 days). Thirty-day adverse events included 2 patients with pericardial effusion requiring pericardiocentesis and 1 incisional hernia repair. There were no long-term complications, strokes, or deaths. LAA ligation was complete in 27 of 33 subjects (82%), with 6 subjects having leaks of <5 mm.

CONCLUSIONS

Subxiphoid hybrid epicardial-endocardial ablation with LAA ligation is feasible, safe, and effective. Future prospective studies are needed to validate these initial findings.

The Convergent Atrial Fibrillation Ablation Procedure: Evolution of a Multidisciplinary Approach to Atrial Fibrillation Management

The treatment of AF has evolved over the past decade with increasing use of catheter ablation in patients refractory to medical therapy. While pulmonary vein isolation using endocardial catheter ablation has been successful in paroxysmal AF, the results have been more controversial in patients with long-standing persistent AF where extrapulmonary venous foci are increasingly recognised in the initiation and maintenance of AF. Hybrid ablation is the integration of minimally invasive epicardial ablation with endocardial catheter ablation, and has been increasingly used in this population with better results. The aim of this article was to analyse and discuss the evidence for the integration of catheter and minimally invasive surgical approaches to treat AF with specific focus on convergent ablation and exclusion of the left atrial appendage using a surgically applied clip.

Catheter Ablation in the Treatment of Atrial Fibrillation

Catheter ablation (CA) of the pulmonary veins for atrial fibrillation (AF) is growing exponentially and is the most commonly performed electrophysiologic procedure. Initial descriptions focused on CA for paroxysmal AF, and now more recently expanded in application to persistent AF and those with comorbid heart failure. Efforts to improve success have and continue to address issues such as pulmonary vein "reconnection" following ablation through different ablative energy modalities, and the use of a "hybrid" surgical/endocardial combined approach in persistent forms of AF. Technologic advances as well are concurrently seeking to improve safety, particularly regarding the incidence of atrio-esophageal fistula in this seemingly ever-growing ablation population.

Morphological and functional parameters of left atrial appendage play a greater role in atrial fibrillation relapse after radiofrequency ablation

This study was to quantitatively investigate the role of morphological and functional parameters of the left atrium (LA) and left atrial appendage (LAA) with 256-slice spiral computed tomography (CT) in the recurrence of atrial fibrillation (AF) after radiofrequency ablation (RFA). Eighty-three patients with AF who underwent RFA for the first time were divided into the recurrence (n = 27) and non-recurrence (n = 56) groups. All patients underwent a 256-slice spiral CT examination before the operation. The clinical data and quantitative measurement of the morphology and functional parameters of the LA and LAA were analyzed, including the maximal and minimal volume, ejection fraction and volume, and volume strain of LAA and LA (LAAVmax, LAAVmin, LAAEF, LAAEV, and LAA-VS, LAVmax, LAVmin, LAEF, LAEV and LA-VS, respectively). The CHA2DS2-VASc score and the proportion of patients with heart failure were significantly (P < 0.05) higher in the recurrence than non-recurrence group. The LAAVmax, LAAVmin, LAVmax, LAVmin, LAAV and LAV were all significantly greater in the recurrence than non-recurrence group (P < 0.05), and the perimeter, major and minor axes of LAA orifice and LAA depth were also significantly greater in the recurrence than non-recurrence group. The LAAEF, LAEF and LAA-VS were significantly (P < 0.05) lower in the recurrence than non-recurrence group (P < 0.05). Heart failure, CHA2DS2-VASC score, LAEF, LAV, LAAEF and LAA-VS were univariately significant (P < 0.05) risk factors for AF recurrence after ablation. Multivariate analysis revealed LAAEF (HR: 0.790, 95% CI: 0.657–0.950, P = 0.012) and LAAV (HR: 1.160, 95% CI: 1.095–1.229, P <0.001) to be two significant independent predictors of recurrence. ROC curve analysis showed that LAAEF <44.68% had the highest predictive value for recurrence after radiofrequency ablation, with the sensitivity of 90% and specificity of 67.4%, whereas LAA volume >9.25 ml had the highest predictive value for AF recurrence after RFA, with the sensitivity of 85.2% and specificity of 67.9%. In conclusion, the volume of left atrium, volume and morphology of left atrial appendage have all significantly increased while the ejection fraction and volume strain of left atrium and left atrial appendage have both significantly decreased in recurrence than in non-recurrence after radiofrequency ablation. The ejection fraction and volume of left atrial appendage are significant independent predictors of atrial fibrillation recurrence after radiofrequency ablation.

Determining a Bayesian predictive power stopping rule for futility in a non-inferiority trial with binary outcomes

Background/Aims

Non-inferiority trials investigate whether a novel intervention, which typically has other benefits (i.e., cheaper or safer), has similar clinical effectiveness to currently available treatments. In situations where interim evidence in a non-inferiority trial suggests that the novel treatment is truly inferior, ethical concerns with continuing randomisation to the “inferior” intervention are raised. Thus, if interim data indicate that concluding non-inferiority at the end of the trial is unlikely, stopping for futility should be considered. To date, limited examples are available to guide the development of stopping rules for non-inferiority trials.

Methods

We used a Bayesian predictive power approach to develop a stopping rule for futility for a trial collecting binary outcomes. We evaluated the frequentist operating characteristics of the stopping rule to ensure control of the Type I and Type II error. Our case study is the Intranasal Ketamine for Procedural Sedation trial (INK trial), a non-inferiority trial designed to assess the sedative properties of ketamine administered using two alternative routes.

Results

We considered implementing our stopping rule after the INK trial enrols 140 patients out of 560. The trial would be stopped if 12 more patients experience a failure on the novel treatment compared to standard care. This trial has a type I error rate of 2.2% and a power of 80%.

Conclusions

Stopping for futility in non-inferiority trials reduces exposure to ineffective treatments and preserves resources for alternative research questions. Futility stopping rules based on Bayesian predictive power are easy to implement and align with trial aims.

Trial registration

ClinicalTrials.gov NCT02828566 July 11, 2016.

•

It is important to consider stopping for futility in non-inferiority trials.

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We develop a rule to stop a non-inferiority trial using Bayesian predictive power.

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We provide code and an online application to implement this method.

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We reduce the complexity of developing stopping rules in non-inferiority trials.

A collective European experience with left atrial appendage suture ligation using the LARIAT+ device

Aims

We report the collective European experience of percutaneous left atrial appendage (LAA) suture ligation using the recent generation LARIAT+ suture delivery device.

Methods and results

A total of 141 patients with non-valvular atrial fibrillation and contraindication to oral anticoagulation (OAC), thrombo-embolic events despite OAC or electrical LAA isolation were enrolled at seven European hospitals to undergo LAA ligation. Patients were followed up by clinical visits and transoesophageal echocardiography (TOE) following LAA closure. Left atrial appendage ligation was completed in 138/141 patients (97.8%). Three patients did not undergo attempted deployment of the LARIAT device due to pericardial adhesion after previous epicardial ventricular tachycardia ablation (n = 1), a pericardial access-related complication (n = 1), and multiple posterior LAA lobes (n = 1). Serious 30-day procedural adverse events occurred in 4/141 patients (2.8%). There were two device-related LAA perforations (1.4%) not resulting in any corrective intervention as the LAA was completely sealed with the LARIAT. Minor adverse events occurred in 19 patients (13.5%), including two pericardial effusions due to procedure-related pericarditis requiring pericardiocentesis. Transoesophageal echocardiography was performed after LAA ligation in 103/138 patients (74.6%) after a mean of 181 ± 72 days. Complete LAA closure was documented in 100 patients (97.1%). Two patients (1.8% of patients with follow-up) experienced a transient ischaemic attack at 4 and 7 months follow-up, although there was no leak observed with TOE. There were two deaths during long-term follow-up which were both not device related.

Conclusion

Initial experience with the LARIAT+ device demonstrates feasibility of LAA exclusion. Further larger prospective studies with longer follow-up are warranted.

Region-specific parasympathetic nerve remodeling in the left atrium contributes to creation of a vulnerable substrate for atrial fibrillation

Atrial fibrillation (AF) is the most common heart rhythm disorder and a major cause of stroke. Unfortunately, current therapies for AF are suboptimal, largely because the molecular mechanisms underlying AF are poorly understood. Since the autonomic nervous system is thought to increase vulnerability to AF, we used a rapid atrial pacing (RAP) canine model to investigate the anatomic and electrophysiological characteristics of autonomic remodeling in different regions of the left atrium. RAP led to marked hypertrophy of parent nerve bundles in the posterior left atrium (PLA), resulting in a global increase in parasympathetic and sympathetic innervation throughout the left atrium. Parasympathetic fibers were more heterogeneously distributed in the PLA when compared with other left atrial regions; this led to greater fractionation and disorganization of AF electrograms in the PLA. Computational modeling revealed that heterogeneously distributed parasympathetic activity exacerbates sympathetic substrate for wave break and reentry. We further discovered that levels of nerve growth factor (NGF) were greatest in the left atrial appendage (LAA), where AF was most organized. Preferential NGF release by the LAA - likely a direct function of frequency and regularity of atrial stimulation - may have important implications for creation of a vulnerable AF substrate.

The left atrial appendage in humans: structure, physiology, and pathogenesis

For many years, the left atrial appendage (LAA) was considered a dormant embryological remnant; however, it is a structurally complex and functional organ that contributes to cardiac haemodynamic changes and volume homeostasis through both its contractile properties and neurohormonal peptide secretion. When dysfunctional, the LAA contributes to thrombogenesis and subsequent increased predisposition to cardioembolic events. Consequently, the LAA has gained much attention as a therapeutic target to lower this risk. In addition, attention has focused on the LAA in its role as an electrical trigger for atrial tachycardia and atrial fibrillation with ablation of the LAA to achieve electrical isolation showing promising results in the maintenance of sinus rhythm. This in-depth review explores the structure, physiology and pathophysiology of the LAA, as well as LAA intervention and their sequelae.

Clinical predictors of acute hyponatremia following LARIAT ligation of the left atrial appendage

INTRODUCTION

Hyponatremia commonly follows percutaneous exclusion of the left atrial appendage (LAA) with the LARIAT suture delivery device. The aim of this study was to evaluate for clinical predictors hyponatremia following ligation of the appendage with the LARIAT device.

METHODS AND RESULTS

A retrospective analysis was conducted on 61 consecutive patients (average age 69.7 ± 9.8 years, 55.7% male) who underwent successful appendage ligation with the LARIAT device. Acute hyponatremia (AH) was defined as a drop in serum sodium (Na) by greater than or equal to 4 mmol/L within 48 hours of ligation while exaggerated acute hyponatremia (EAH) was defined as a drop greater than or equal to 10 mmol/L. Among all patients, there was a significant decrease in [Na] at 24 hours (3.26 ± 2.77 mmol/L) and 48 hours (4.98 ± 3.74 mmol/L). Thirty-two patients (52.4%) had AH while six patients (9.8%) experienced EAH. A body mass index (BMI) of less than 28.4 kg/m² was associated with AH (P = .037) while a BMI < 25 kg/m² was associated with EAH (P = .021). A linear regression analysis comparing the maximum sodium decrease to the indexed left atrial (LA) diameter found that for every 1 cm/m² increase in indexed LA diameter, there was a 2.5 mEq/L decrease in serum sodium (P = .04).

CONCLUSIONS

Hyponatremia frequently occurs following LAA ligation with the LARIAT device. A low BMI < 25 kg/m² is associated with a drop in serum sodium of greater than 10 mmol/L while increasing indexed LA diameter predicts any AH. AH is also associated with a significantly lower systolic blood pressure 48 to 72 hours post LAA exclusion with the LARIAT device.

Left Atrial Appendage Occlusion for The Unmet Clinical Needs of Stroke Prevention in Nonvalvular Atrial Fibrillation

Oral anticoagulation is the dominant strategy for stroke prevention in patients with nonvalvular atrial fibrillation. However, lifelong oral anticoagulation is associated with major issues including inappropriate dosing, nonadherence, and adverse effects. Therefore, efforts have been made to develop site-specific therapy aimed to occlude the left atrial appendage, the anatomical site accountable for more than 90% of nonvalvular atrial fibrillation-related ischemic strokes. This review focuses on the growing literature to put into perspective the risk-balance ratio of left atrial appendage occlusion.

Persistent Atrial Fibrillation Ablation: Where Do We Go From Here?

Catheter ablation is being used increasingly for the treatment of atrial fibrillation (AF). Pulmonary vein antral isolation is considered the "cornerstone" for the ablation of AF. This approach has demonstrated consistent rates of success for paroxysmal AF, but the rates of success for persistent AF are lower. There has long been a hypothesis that additional ablation beyond pulmonary vein isolation is required to achieve better outcomes in the population with persistent AF. However, large clinical trials have demonstrated recently that such approaches as empiric linear ablation and/or ablation of complex fractionated electrograms may add no benefit over pulmonary vein isolation alone in persistent AF. Furthermore, new technologies are improving the durability and outcome of pulmonary vein isolation alone. These observations have endorsed a search for new potential targets for adjuvant ablation, which currently include ablation of dynamic phenomena during AF such as rotational and focal activations, ablation of scar regions in the atria, isolation of the left atrial posterior wall, and ablation of nonpulmonary vein triggers. Whether any of these additional approaches will add to the success of ablation for persistent AF is unknown. Smaller study results are mixed. Only the performance of large-scale randomized trials will definitively answer whether additional ablation over pulmonary vein isolation alone with improve outcomes for persistent AF.

The Left Atrial Appendage, Including LAA Occlusion Devices Line Watchman, Amulet, and Lariat

Atrial fibrillation is a very common arrhythmia whose prevalence is expected to increase significantly as the population ages. The associated stroke risk is a major cause of morbidity and mortality. Stroke prevention by anticoagulation carries its own risks, leading to the search for alternative strategies. Multiple techniques have been developed to exclude the left atrial appendage (the main source of thromboembolism in atrial fibrillation) from the circulation. Such techniques offer the hope of stroke prevention without the risks of anticoagulation. This article describes the percutaneous approaches being currently performed in the United States. Particular emphasis is placed on the use of transesophageal echocardiography to guide these procedures.

Subxiphoid Hybrid Approach for Epicardial/Endocardial Ablation and LAA Exclusion in Patients with Persistent and Longstanding Atrial Fibrillation

Two patients with long-standing atrial fibrillation (AF) refractory to medical management and with prior pulmonary vein isolation underwent a new hybrid epicardial/endocardial subxyphoid approach for AF ablation and left atrial appendage (LAA) ligation. Pulmonary vein and LA posterior wall isolation, as well as LAA exclusion were achieved in both patients. There were no procedural complications. Both patients remain in sinus rhythm. Both patients are off antiarrhythmic medications.

LARIAT Trial Updates

The thrombus formed within the LAA is responsible for the vast (about 90%) majority of strokes. Anticoagulation, although effective therapy for stroke prevention is not feasible in a significant minority of patients due to various reasons. Two percutaenous LAA exclusion techniques have been developed in an effort to decrease risk for stroke: endocardial closure/plugging of the LAA (Watchman, Amplatzer devices) and epicardial LAA ligation (LARIAT). The aim of this study is to review the trial data to date for the LARIAT device. The LARIAT suture has been used in more than 4500 patients with high success of LAA complete closure (92-100%), mostly in the patients unable to take anticoagulation and in a small minority as antiarrhythmic option. The LARIAT technique has evolved with a change in pericardial access method that resulted in dramatic improvement of safety. LAA closure performance with LARIAT system seems to be similar to Watchman device, with small leaks during follow-up in 6-24% of the cases, which do not to correlate with thrombo-embolic events. LAA has been proven to play an important triggering role in patients with persistent atrial fibrillation. Small studies had shown that LAA ligation with LARIAT could terminate persistent atrial fibrillation and possible improve ablation success. Ongoing aMAZE randomized trial is studying if LAA ligaiton using LARIAT suture leads to improved atrial fibrillation ablation success. Available data suggests that LAA closure using LARIAT epicardial suture is a good alternative for stroke risk reduction in patients who are unable to be on anticoagulation therapy. LARIAT system might improve success of AF ablation for patients with persistent and long persistent AF, pending the results of the ongoing aMAZE trial.

The Year in Perioperative Echocardiography: Selected Highlights from 2017

This article is the second of an annual series reviewing the research highlights of the year pertaining to the subspecialty of perioperative echocardiography for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor-in-chief, Dr. Kaplan, and the editorial board for the opportunity to start this series. In most cases, these will be research articles that are targeted at the perioperative echocardiography diagnosis and treatment of patients after cardiothoracic surgery; however, in some cases, these articles will target the use of perioperative echocardiography in general.

Left Atrial Appendage Occlusion: What Are the Options and Where is the Evidence?

Left atrial appendage occlusion (LAAO) has emerged as an effective site-directed therapy in patients with nonvalvular atrial fibrillation (AF) for stroke prevention, who are ineligible for long-term oral anticoagulation. The objective of this study was to assess the safety, efficacy, and availability of LAAO devices by reviewing the literature and to review the development and effectiveness of LAAO by the transcatheter approach with plugging devices such as WATCHMAN™ (Boston Scientific, Natick, MA, USA); AMPLATZER™ Cardiac Plug and AMPLATZER™ Amulet™ (Abbott Laboratories, Chicago, IL, USA); and the LARIAT^® Suture Delivery Device (SentreHEART, Redwood City, CA, USA), which features an entirely unique hybrid (endocardial and epicardial) approach in closing the left atrial appendage (LAA). The conducted literature review ultimately revealed a substantial body of literature supporting the safety and efficacy of various LAAO strategies, including endocardial, epicardial, and hybrid approaches, in AF patients who are not eligible for long-term oral anticoagulant use. Specifically, the most attractive population suitable for LAA closure appears to be patients at high risk for ischemic stroke with a longer life expectancy but a moderate-to-high bleeding risk with long-term oral anticoagulation. The benefit of LAA closure in reducing the incidence of stroke in patients with nonvalvular AF has been evolving gradually, and we are confident that this new field of percutaneous LAA closure will continue to emerge as a game-changer in the treatment of AF.

Indication, Patient Selection, and Referral Pathways for Left Atrial Appendage Closure

Left atrial appendage closure (LAAC) has emerged as a viable option for stroke prevention, especially in those intolerant of or not suitable for long-term oral anticoagulation therapy. This article describes the clinical characteristics, indications, and a proposed referral system for potential LAAC patients. Patient selection remains a challenge because of the paradox between the available randomized data on this intervention and the actual patient population who may gain maximum benefit. Further investigations comparing different LAAC devices with each other and with novel oral anticoagulants are needed. Also, the optimal antithrombotic regimen post-procedure has yet to be determined.

Bayesian adaptive trials for rare cardiovascular conditions

Escalating costs of cardiovascular trials are limiting medical innovations, prompting the development of more efficient and flexible study designs. The Bayesian paradigm offers a framework conducive to adaptive trial methodologies and is well suited for the study of small populations. Bayesian adaptive trials provide a statistical structure for combining prior information with accumulating data to compute probabilities of unknown quantities of interest. Adaptive design features are useful in modifying randomization schemes, adjusting sample sizes and providing continuous surveillance to guide decisions on dropping study arms or premature trial interruption. Advantages include greater efficiency, minimization of risks, inclusion of knowledge as it is generated, cost savings and more intuitive interpretability. Extensive high-level computations are facilitated by an expanding armamentarium of available tools.

Hybrid and surgical procedures for the treatment of persistent and longstanding persistent atrial fibrillation

INTRODUCTION

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The incidence of AF increases with age and is associated with increased stroke, heart failure and mortality. Persistent and long standing persistent AF is difficult to treat and often refractory to medical therapy and catheter ablation. Areas covered: This article reviews the historical development of the surgical Cox-MAZE procedure and current hybrid and minimally invasive surgical approaches for the treatment of persistent and long standing persistent AF. The role of concomitant pulmonary vein isolation and left atrial appendage (LAA) exclusion will also be reviewed. Expert commentary: An ablation pattern emulating the Cox-Maze surgical procedure is commonly needed to obtain maintenance of sinus rhythm in patients with persistent and long standing persistent atrial fibrillation. Minimally invasive bilateral thorascopic surgical procedures can achieve a similar Cox-Maze lesion set, but are associated with increased adverse events compared to catheter ablation. Future prospective randomized studies are required to confirm whether the recently developed hybrid subxyphoid epicardial/endocardial procedure and percutaneous LAA ligation and catheter ablation are indeed as effective as surgical options with less adverse events.