Elimination of the Left Atrial Appendage To Prevent Stroke or Embolism?

Is It Safe to Preserve Left Atrial Appendage During Maze Procedure?

BACKGROUND AND OBJECTIVES

The left atrial appendage (LAA) can contribute significantly to LA mechanical contraction. Nevertheless, the preventive effect of LAA occlusion during the maze procedure against cerebral infarction remains controversial. In this study, we compared the surgical, cardiac hemodynamic, and neurologic outcomes between LAA preservation and occlusion performed during the maze procedure.

METHODS

Between January 2015 and August 2021, 252 patients underwent the maze procedure using cryoablation at our medical center. After excluding patients according to our exclusion criteria (i.e., mechanical prosthesis implantation, preexisting LAA thrombus), LAA was preserved in 113 patients (non-occlusion group) and occluded in 75 patients (occlusion group). Outcomes were compared using propensity score matching (PSM).

RESULTS

PSM did not reveal significant intergroup differences in baseline characteristics between the non-occlusion (n=53) and occlusion (n=53) groups. During a median follow-up of 44 months, 2 patients in the non-occlusion group (3.8%) experienced ischemic strokes. There was no significant difference in the rate of freedom from stroke (p=0.19) and major adverse cardiac events (p=0.43) between the 2 groups. Through echocardiography at 1-year follow-up, a statistically significant difference in LA mechanical contraction was observed between the non-occlusion group and occlusion group (24 of 33 [72.7%] vs. 18 of 37 [48.6%], respectively; p=0.04).

CONCLUSIONS

In this study, preservation of the LAA during the maze procedure resulted in better LA function than LAA occlusion, with similar rates of stroke.

Left Atrial Thrombus-Are All Atria and Appendages Equal?

Although the left atrial appendage (LAA) seems useless, it has several critical functions that are not fully known yet, such as the causes for being the main origin of cardioembolic stroke. Difficulties arise due to the extreme range of LAA morphologic variability, making the definition of normality challenging and hampering the stratification of thrombotic risk. Furthermore, obtaining quantitative metrics of its anatomy and function from patient data is not straightforward. A multimodality imaging approach, using advanced computational tools for their analysis, allows a complete characterization of the LAA to individualize medical decisions related to left atrial thrombosis patients.

Metabolic Effects of the Left Atrial Appendage Exclusion (THE HEART HORMONE STUDY)

OBJECTIVE

The effect of epicardial LAA occlusion therapy on lipid and glucose metabolism in AF patients over the long term follow up is unclear.

METHODS

In a single-center prospective observational study, 60 patients with longstanding persistent AF with cardiovascular risk factors had undergone an epicardial exclusion procedure. Anthropometric parameters and glucose, glycated hemoglobin (HbA1c), insulin, leptin, adiponectin, free fatty acids, beta-hydroxybutyrate, and total cholesterol levels were evaluated on fasting at baseline before the procedure and compared with levels at 24 hours, 7 days, 1 month, 3 months, 6 months, and 24 months follow the procedure.

RESULTS

The mean age of the patients was 67.5 ± 8.1. Insulin levels significantly increased at 7 days, 1 month, 3 months, 6 months, 12 months, and 24 months follow-up. The leptin levels showed a significant increase in 6 months, 12 months, and 24 months when compared to baseline. Whereas the adiponectin levels showed a significant decrease at 3 months, 6 months, 12 months, and 24 months when compared to baseline levels. In patients with the epicardial procedure, when compared to baseline, glucose, glycated hemoglobin, total cholesterol, and beta-hydroxybutyrate levels did not show any significant changes at baseline and 24 months follow up.

CONCLUSION

The epicardial exclusion ligation in AF patients was associated with significant changes in insulin, leptin, and adiponectin over long follow up. This article is protected by copyright. All rights reserved.

Left Atrial Thrombus-Are All Atria and Appendages Equal?

Although the left atrial appendage (LAA) seems useless, it has several critical functions that are not fully known yet, such as the causes for being the main origin of cardioembolic stroke. Difficulties arise due to the extreme range of LAA morphologic variability, making the definition of normality challenging and hampering the stratification of thrombotic risk. Furthermore, obtaining quantitative metrics of its anatomy and function from patient data is not straightforward. A multimodality imaging approach, using advanced computational tools for their analysis, allows a complete characterization of the LAA to individualize medical decisions related to left atrial thrombosis patients.

Machine Learning Identifies Six Genetic Variants and Alterations in the Heart Atrial Appendage as Key Contributors to PD Risk Predictivity

Parkinson's disease (PD) is a complex neurodegenerative disease with a range of causes and clinical presentations. Over 76 genetic loci (comprising 90 SNPs) have been associated with PD by the most recent GWAS meta-analysis. Most of these PD-associated variants are located in non-coding regions of the genome and it is difficult to understand what they are doing and how they contribute to the aetiology of PD. We hypothesised that PD-associated genetic variants modulate disease risk through tissue-specific expression quantitative trait loci (eQTL) effects. We developed and validated a machine learning approach that integrated tissue-specific eQTL data on known PD-associated genetic variants with PD case and control genotypes from the Wellcome Trust Case Control Consortium. In so doing, our analysis ranked the tissue-specific transcription effects for PD-associated genetic variants and estimated their relative contributions to PD risk. We identified roles for SNPs that are connected with INPP5P, CNTN1, GBA and SNCA in PD. Ranking the variants and tissue-specific eQTL effects contributing most to the machine learning model suggested a key role in the risk of developing PD for two variants (rs7617877 and rs6808178) and eQTL associated transcriptional changes of EAF1-AS1 within the heart atrial appendage. Similarly, effects associated with eQTLs located within the Brain Cerebellum were also recognized to confer major PD risk. These findings were replicated in two additional, independent cohorts (the UK Biobank, and NeuroX) and thus warrant further mechanistic investigations to determine if these transcriptional changes could act as early contributors to PD risk and disease development.

Does Left Atrial Appendage Exclusion by an Epicardial Clipinfluence Left Atrial Hemodynamics? Pilot Results of Invasive Intra-Cardiac Measurements

Left atrial appendage (LAA) exclusion is the cornerstone of stroke prevention in surgical treatment of atrial fibrillation (AF). Still, little is known about the direct hemodynamic consequences of LAA closure. In the current pilot study, where we aimed to evaluate these consequences in patients undergoing hybrid AF ablation with LAA exclusion by an atrial clip, seven patients were included. Hemodynamic and intracardiac pressure measurements such as systemic, pulmonary artery (PA), central venous and LA pressure, cardiac output and indexed left ventricular stroke volume (LVSVi) were measured directly before (T0) and after (T1), and 10 minutes after (T2) LAA closure. We found no differences between all timepoints for LA pressure, PA pressure and LVSVi. As such, this is the first study describing the direct hemodynamic consequences of LAA exclusion. LAA exclusion by use of an atrial clip is safe and does not directly affect hemodynamic and intracardiac pressures.

Predictors of Subsequent Heart Failure After Left Atrial Appendage Closure

BACKGROUND

Left atrial appendage occlusion (LAAO) plays an important role in preventing stroke in patients with atrial fibrillation. However, LAAO may interact unfavorably with left atrial (LA) compliance and reservoir function and thus increase the risk of heart failure (HF). The purpose of this study was to identify predictors of subsequent HF after successful LAAO.Methods and Results:A total of 98 patients (mean age 70±9 years, 68% male) who had undergone LAAO were included. The primary endpoint was unexpected HF admission after LAAO. During a mean period of 36±26 months, 16 of the 98 patients (16%) experienced hospital HF admission. In multivariate analysis, higher E/e' (hazard ratio [HR] 1.11, 95% confidence interval [CI] 1.02-1.20, P=0.014), higher left ventricular mass index (HR 1.02, 95% CI 1.00-1.03, P=0.023), history of HF (HR 4.78, 95% CI 1.55-14.7, P=0.006), and lower LA strain (HR 0.80, 95% CI 0.70-0.93, P=0.003) were independently associated with hospital HF admission. Patients with LAAO had a significantly higher incidence of subsequent HF than the control group after propensity score matching (P=0.046).

CONCLUSIONS

LAAO increases the occurrence of HF, and it is not uncommon after successful LAAO. A previous history of HF, left ventricular mass index, E/e', and abnormal LA strain are independently associated with the development of HF. These parameters should be considered before attempting LAAO.

A 79-year-old woman with atrial fibrillation and new onset of heart failure

As an alternative to oral anticoagulation, percutaneous left atrial appendage (LAA) closure is an increasingly performed procedure to prevent arterial embolism in patients with non‐valvular atrial fibrillation. Besides procedure‐related complications, residual leaks, device‐related thrombus formation, and dislocation of the LAA occluder have been observed during follow‐up. Heart failure as a consequence of interventional LAA closure has not been reported so far. This case report describes a 79‐year‐old lady with permanent non‐valvular atrial fibrillation presenting with New York Heart Association Class IV heart failure. Symptoms had started immediately after attempted LAA closure 11 months before. Transoesophageal echocardiography demonstrated two devices in the LAA, a large peri‐device leak, a mobile LAA thrombus, a right atrial appendage thrombus, and shunting via a patent foramen ovale. Under a maximally tolerated dose of heart failure medication and edoxaban, the patient remains without bleeding or embolism in New York Heart Association Class II. Because of its unique anatomical and endocrine properties, the LAA plays an important role in situations of pressure and volume overload. Interventional LAA closure interacts unfavourably with left atrial compliance and reservoir function. Atrial and brain natriuretic peptide secretion is known to be significantly reduced after LAA closure. Both mechanisms may result in the development of heart failure. Attempted LAA closure—instead of being the solution—may create new serious problems. Development of heart failure should be assessed, and a systematic search for late leaks after LAA closure should be performed in trials investigating safety and efficacy of this intervention.

Hemodynamic impact of percutaneous left atrial appendage closure in patients with paroxysmal atrial fibrillation

PURPOSE

Percutaneous left atrial appendage (LAA) closure has become a valid alternative to anticoagulation therapy for the prevention of thromboembolic events in patients with atrial fibrillation (AF). However, scarce data exist on the impact of LAA closure on left atrial and ventricular function. We sought to assess the acute hemodynamic changes associated with percutaneous LAA closure in patients with paroxysmal AF.

METHODS

The study population consisted of 31 patients (mean age 73 ± 10 years; 49% women) with paroxysmal AF who underwent successful percutaneous LAA closure. All patients were in sinus rhythm and underwent 2D transthoracic echocardiography at baseline and the day after the procedure. A subset of 14 patients underwent preprocedural cardiac computed tomography (CT) with 3D LA and LAA reconstruction.

RESULTS

Left ventricular systolic function parameters and LA volumetric indexes remained unchanged after the procedure. No significant changes in left ventricular stroke volume (72.4 ± 16.0 vs. 73.3 ± 15.7 mL, p = 0.55) or LA stroke volume (total 15.6 ± 4.2 vs. 14.6 ± 4.2 mL, p = 0.21; passive 9.0 ± 2.8 vs. 8.3 ± 2.6 mL, p = 0.31; active 10.3 ± 5.6 vs. 10.0 ± 6.4 mL, p = 0.72) occurred following LAA closure. Mean ratio of LAA to LA volume by 3D CT was 10.2 ± 2.3%. No correlation was found between LAA/LA ratio and changes in LA stroke volume (r = 0.35, p = 0.22) or left ventricular stroke volume (r = 0.28, p = 0.33).

CONCLUSIONS

The LAA accounts for about 10% of the total LA volume, but percutaneous LAA closure did not translate into any significant changes in LA and left ventricular function.

Percutaneous Closure of Left Atrial Appendage significantly affects Lipidome Metabolism

Patients with non-valvular atrial fibrillation (AF) and a high risk for oral anticoagulation can be treated by percutaneous implantation of left atrial appendage occlusion devices (LAAC) to reduce the risk of cardio-embolic stroke. This study evaluates whether LAAC may influence lipid metabolism, which has never been investigated before. Patients with successful LAAC were included consecutively. Venous peripheral blood samples of patients were collected immediately before (T0, baseline) and 6 months after (T1, mid-term) LAAC. A targeted metabolomics approach based on electrospray ionization liquid chromatography-mass spectrometry (ESI-LC-MS/MS) and MS/MS measurements was performed. A total of 34 lipids revealed a significant change from baseline to mid-term follow-up after successful LAAC. Subgroup analysis revealed confounding influence by gender, age, diabetes mellitus type II, body mass index, left ventricular ejection fraction, creatinine and NT-proBNP. After multivariable adjustment within logistic regression models, these 34 lipids were still significantly altered after LAAC. Successful percutaneous LAAC may affect lipid metabolism and thereby may potentially affect pro-atherogenic and cardio-toxic effects.

Occlusion of left atrial appendage affects metabolomic profile: focus on glycolysis, tricarboxylic acid and urea metabolism

BACKGROUND

Left atrial appendage (LAA) closure (LAAC) by implantation of an occlusion device is an established cardiac intervention to reduce risk of stroke while avoiding intake of oral anticoagulation medication during atrial fibrillation. Cardiac interventions can alter local or systemic gene and protein expression. Effects of LAAC on systemic metabolism have not been studied yet.

OBJECTIVES

We aimed to study the effects of interventional LAAC on systemic metabolism.

METHODS

Products of glycolysis, tricarboxylic acid and urea metabolism were analyzed by ESI-LC-MS/MS and MS/MS using the AbsoluteIDQ™ p180 Kit in plasma of 44 patients undergoing successful interventional LAAC at baseline (T0) and after 6 months (T1).

RESULTS

During follow up, plasma concentrations of several parameters of glycolysis and tricarboxylic acid cycle (TCA) and urea metabolism increased (alanine, hexose, proline, sarcosine), while others decreased (aspartate, glycine, SDMA, serine). Multivariate linear regression analysis showed that time after interventional LAAC was an independent predictor for metabolite changes, including the decrease of SDMA (beta -0.19, p < 0.01) and the increase of sarcosine (beta 0.16, p < 0.01).

CONCLUSIONS

Successful interventional LAAC affects different pathways of the metabolome, which are probably related to cardiac remodeling. The underlying mechanisms as well as the long term effects have to be studied in the future.

Morphological changes evaluation of left atrial appendage in patients with ischaemic heart disease

BACKGROUND

Since the majority of morphological changes evaluation of myocardium in ischaemic heart disease was in animal model, we detected the importance to evaluate such changes in human patients to gain insights into the targets of cellular damage and to reconcile or refine those experiments.

METHODS

Tissue sections from left atrial appendage of the heart were carefully dissected from seventy five patients underwent conventional coronary artery bypass grafting at the cardiothoracic surgical department, Manchester Royal Infirmary. Tissue was fixed, sectioned, stained and six random sections were photographed and the images were assessed and quantified using Image Analyser Pro-Plus software, version 4.1. Arterioles, venules, intermediate sized vessels, and capillaries were directly counted within the highlighted area of myocardium under LM. Ultra-thin sections were imaged in a Tecnai 12 Biotwin transmission electron microscope at a magnification of ×4200 and photographed by a camera with a black and white film to quantify different structures of myocardium.

RESULTS

The arteriole wall to lumen ratio was significantly increased in ischaemic heart disease patients 18.57 ± 2.89 compared to controls 8.3 ± 1.57, (P < 0.01). The regression analysis between vascular density and cardiomyocyte size demonstrated a significant inverse correlation between transverse cardiomyocyte diameter and arteriole, capillary and total vessel density (P < 0.01, 0.04, 0.02), respectively. Lumen area of the distal myocardial capillary was significantly reduced in IHD patients compared to controls (P < 0.01).

CONCLUSION

These results elucidate the morphological changes in the myocardial microvasculature of patients with ischaemic heart disease and its pathological magnitudes.

Complete Obliteration of the Left Atrial Appendage: An Analysis of Epicardial Excision and Novel Pericardial Patch Exclusion

OBJECTIVE

Conventional epicardial excision is believed to be the most effective method of surgically obliterating the left atrial appendage (LAA), although incomplete resection and residual LAA volume may undermine its effectiveness. We sought to compare the impact of conventional epicardial excision with a novel LAA pericardial patch exclusion on residual LAA volume.

METHODS

We performed LAA obliteration using pericardial patch exclusion, followed by conventional epicardial excision, in 27 cadaveric hearts. After each procedure, residual LAA volume was measured by two different techniques and compared with baseline volume. There was no difference in baseline LAA volume between each procedure.

RESULTS

Procedural success was achieved in all hearts. Conventional epicardial excision left a residual LAA volume of 0.95 mL (24%), as compared with pericardial patch exclusion, which left a residual volume of 0.17 mL (4%, P = 0.0001). Further analysis of fixed and fresh hearts showed that reduction of LAA volume was more pronounced in the fresh hearts, suggesting effectiveness in live patients. Neither technique resulted in any significant change in the endocardial shape of the LAA orifice or injury to the circumflex artery.

CONCLUSIONS

Conventional epicardial excision of the LAA results in significantly more residual LAA volume, which may have important implications in persistent stroke risk. Pericardial patch exclusion seems to achieve near-total elimination of the LAA and may be a superior surgical option.

Incidence of thromboembolism following detection by trans-oesophageal echocardiography of left atrial thrombus

Background

Left atrial appendage (LAA) thrombus is an accepted risk factor for ischemic stroke. Following a literature review we were unable to identify a study that determined the incidence of ischemic stroke in patients with a confirmed LAA thrombus. The purpose of this study was to establish the incidence of ischemic stroke in patients with a LAA thrombus confirmed on trans-oesophageal echocardiography (TOE).

Method

A ten year retrospective single centre study was conducted for the period March 2005 to February 2014 in St. Vincent's University Hospital, Ireland. All TOE studies performed during this period were reviewed. A chart review was carried out on any patient who had a LAA thrombus, left atrial (LA) thrombus or pre-thrombus state identified. Charts were reviewed for documented neurological deficits consistent with ischemic stroke or transient ischemic attack within six months following TOE study.

Results

Overall 1903 TOE studies were reviewed. A total of 67 TOE studies detected a LAA thrombus, LA thrombus or pre-thrombus state. In the days prior to TOE, an ischemic stroke had occurred in two of the patients. Following detection of thrombus or pre-thrombus state on TOE and optimization of oral anti-coagulation (OAC), no patient had an ischemic stroke over the subsequent six months.

Conclusion

This is the only study to date that has looked at the incidence of ischemic stroke following a confirmed LAA thrombus, LA thrombus or pre-thrombus state. This single centre study found low stroke rates over a six month follow-up period in patients with a confirmed LAA thrombus, LA thrombus or pre-thrombus state and optimization of OAC. Larger studies would be required to confirm these findings.

A Review Of The Relevant Embryology, Pathohistology, And Anatomy Of The Left Atrial Appendage For The Invasive Cardiac Electrophysiologist

The three-dimensional morphology of the left atrial appendage provides the substrate for thrombus generation, and is a harbinger for embolic material due to its direct connection to the left-sided circulation. Appreciating the development of the appendage from mesodermal layer to its adult form provides the basis to improve exclusion from the atrial circulation, and thereby can lead to a significant reduction in stroke risk. This process also provides insight into the role of the left atrial appendage as an endocrine organ, its involvement in fluid homeostasis, and its connection to the autonomic nervous system. Knowledge of the surrounding structural arrangement is critical to identify landmarks from both an endocardial and epicardial perspective to improve targeted device placement. Furthermore, correlation of the left atrial appendage body, neck, and ostium to the surrounding anatomy can also improve both procedural efficacy and safety. In addition, a working knowledge of the regional anatomy adds a prudent degree of awareness for procedural complications, and allows for early identification and timely intervention as these situations arise. A detailed understanding of the left atrial appendage embryology, histology, and gross anatomy is imperative to identify the correct device and approach for each individual patient. In addition, this increased awareness can identify areas that are in need of further innovation, and thus provide the ability to adapt and refine existing technologies to overcome pitfalls currently facing catheter-based approaches.

Optimization Of Stroke Prophylaxis Strategies In Nonvalvular AF -Drugs, Devices Or Both?

Atrial fibrillation (AF) is the most common cardiac arrhythmia with the prevalence increasing over time. AF probably afflicts ≥2% of worldwide adult population and increases with age.[1-3] In the Framingham Heart Study, the lifetime risk of having at least one episode of AF for 40-year-old men and women was 26% and 23% respectively.[4].

Novel nonpharmacologic approaches for stroke prevention in atrial fibrillation: results from clinical trials

Atrial fibrillation (AF), the most common cardiac arrhythmia, confers a 5-fold risk of stroke that increases to 17-fold when associated with mitral stenosis. At this time, the most effective long-term solution to protect patients from stroke and thromboembolism is oral anticoagulation, either with vitamin K antagonists (VKAs) or a novel oral anticoagulant (NOAC). Despite the significant benefits they confer, both VKAs and NOACs are underused because of their increased potential for bleeding, and VKAs are underused because of their narrow therapeutic range, need for regular international normalized ratio checks, and interactions with food or medications. In patients with nonvalvular AF, approximately 90% of strokes originate from the left atrial appendage (LAA); in patients with rheumatic mitral valve disease, many patients (60%) have strokes that originate from the left atrium itself. Surgical LAA amputation or closure, although widely used to reduce stroke risk in association with cardiac surgery, is not currently performed as a stand-alone operation for stroke risk reduction because of its invasiveness. Percutaneous LAA closure, as an alternative to anticoagulation, has been increasingly used during the last decade in an effort to reduce stroke risk in nonvalvular AF. Several devices have been introduced during this time, of which one has demonstrated noninferiority compared with warfarin in a randomized controlled trial. This review describes the available technologies for percutaneous LAA closure, as well as a summary of the published trials concerning their safety and efficacy in reducing stroke risk in AF.

The three integrated phases of left atrial macrophysiology and their interactions

Our understanding of the left atrium is growing, although there are many aspects that are still poorly understood. The left atrium size as an imaging biomarker has been consistently shown to be a powerful predictor of outcomes and of different cardiovascular disorders, such as, but not limited to, atrial fibrillation, congestive heart failure, mitral regurgitation and stroke. Left atrial function has been conventionally divided into three integrated phases: reservoir, conduit and booster-pump. The highly dynamic left atrium and its response to the stretch and secretion of atrial neuropeptides leaves the left atrium far from being a simple transport chamber. The aim of this review is to provide an understanding of the left atrial physiology and its relation to disorders within the heart.

Left-atrial-appendage occluder migrates in an asymptomatic patient

Percutaneous closure of the left atrial appendage (LAA) is a new approach to the prevention of cardioembolic events in patients with atrial fibrillation. We implanted an LAA occlusion device (Amplatzer™ Cardiac Plug) in a 70-year-old woman via a transseptal approach. Upon her discharge from the hospital, a transthoracic echocardiogram showed stable anchoring of the device; 6 months after implantation, a routine transthoracic echocardiogram revealed migration of the occluder into the left ventricular outflow tract, in the absence of symptoms. We surgically removed the device from the mitral subvalvular apparatus and closed the LAA with sutures. This case shows that percutaneous LAA occlusion can result in serious adverse events, including device migration in the absence of signs or symptoms; therefore, careful follow-up monitoring is mandatory.

Nonpharmacologic stroke prevention in atrial fibrillation

Atrial fibrillation is associated with significant mortality and morbidity. The burden of morbidity in atrial fibrillation is mostly due to stroke, one of the major causes of death and the leading cause of long-term disability. Although highly effective in prevention of thromboembolic stroke, several factors limit utilization of chronic oral anticoagulation therapy. Eradication of atrial fibrillation and restoration of effective atrial contraction by surgical methods, or recently, by percutaneous catheter ablation methods, are two attractive approaches for stroke prophylaxis. Surgical exclusion of the left atrial appendage has generated considerable interest in the past decades and it is now performed routinely during mitral valve surgery in many centers. Recently, minimally invasive and percutaneous methods for the exclusion of left atrial appendage have been introduced. Currently, these approaches are being evaluated in ongoing trials. This review will discuss the current status of nonpharmacologic methods in the prevention of stroke in atrial fibrillation.

Left atrial appendage resection versus preservation during the surgical ablation of atrial fibrillation

BACKGROUND

Left atrial appendage (LAA) resection during the Maze procedure may decrease thromboembolic risks, but its preservation may improve left atrial contractile function. This study compared the clinical effects of LAA resection and preservation after the Maze procedure.

METHODS

A retrospective review was made of 379 patients (mean age 53.3 ± 12.6 years, 244 females) who underwent the cryo-Maze procedure in conjunction with mitral surgery from 1999 to 2011. The LAA was resected in 187 patients (resection group) but preserved in 192 patients (preservation group). Outcomes were compared using a propensity score study design based on 20 baseline characteristics to obtain well-matched patient pairs.

RESULTS

Propensity score matching yielded 119 pairs of patients in whom there were no significant differences in baseline profiles between the two groups. During a mean follow-up of 3.1 ± 2.8 years, there were 16 deaths, 6 cases of stroke, and 39 cases of atrial fibrillation recurrence. There were no significant differences in stroke-free survival (p = 0.88) and freedom from AF while off antiarrhythmic drugs (p = 0.46) between the two groups. On serial echocardiographic assessments, patients in the preservation group showed a higher transmitral A-wave velocity (peak atrial contraction wave velocity; p = 0.47, 0.020, and 0.001 at 3, 6, and 12 months, respectively) and lower E/A ratio (peak early filling wave [E-wave] velocity / A-wave velocity; p = 0.34, 0.065, and 0.001 at 3, 6, and 12 months, respectively) at each timepoint compared with the resection group.

CONCLUSIONS

Preservation of the LAA during the Maze procedure resulted in similar clinical and rhythm outcomes, but LA contractile function superior to that of LAA resection.

Surgical strategies and devices for surgical exclusion of the left atrial appendage: a word of caution

In patients with chronic atrial fibrillation, 90% of clots are located in the left atrial appendage (LAA). Therefore, LAA exclusion is a means of preventing thrombus formation and subsequent thromboembolic events in these patients. The LAA can be excluded from the systemic circulation via surgical, percutaneous, or thoracoscopic approaches. The surgical aim is complete obliteration of the appendage without a significant increase in either postoperative complications (bleeding, arrhythmias) or recurrence. We discuss the current surgical techniques available for LAA obliteration and review their results.

Left atrial and left atrial appendage systolic function in patients with post-myocardial distal blocks

INTRODUCTION

The study aimed to evaluate function of the left atrium (LA) and of the left atrial appendage (LAA) after myocardial infarction (MI) complicated by intracardiac conduction disturbances.

MATERIAL AND METHODS

The study comprised 59 patients with persistent post-myocardial distal blocks, who were allocated to one of the three following subgroups: study group I - 20 patients with left bundle branch block (LBBB); study group II - 20 patients with right bundle branch block (RBBB), and study group III -19 pts with left anterior hemiblock (LAHB). The control groups included patients with MI in their history and no BBBs (19 pts - group IV) and clinically healthy people (16 patients - group V). The parameters of LA and LAA systolic function were determined by means of transthoracic (TTE) and transoesophageal echocardiography (TOE).

RESULTS

We showed that patients who experienced myocardial infarction not complicated with conduction disturbances expressed compensatory LA systolic function enhancement. In patients with post-myocardial RBBB and LAHB significant enhancement of LA systolic function was observed as well but it was expressed to a lesser degree. There was also a tendency towards deterioration of LA systolic function in patients with post-myocardial LBBB. LBBB did not affect LAA systolic function negatively.

CONCLUSIONS

Parameters of LAA systolic function showed its enhancement in all patients after myocardial infarction irrespective of whether it was complicated by conduction disturbances.

Recent progress in antithrombotic therapy for atrial fibrillation

Atrial fibrillation (AF) is becoming a major health care burden as elderly populations increase. The increased risk of stroke and thromboembolisms in patients with AF is well documented and anti-coagulation with adjusted-dose warfarin is highly effective in reducing stroke risk, being superior to antiplatelet agents. Despite recognition of the epidemiological problem and the sound evidence base for thromboprophylaxis, as well as major guidelines recommending treatment, anticoagulation use is still suboptimal, given the dis-utility and limitations associated with warfarin. Recent developments in thromboprophylaxis for AF include efforts for better risk stratification for predictions of thromboembolic risk. Constant efforts are underway to develop newer, less cumbersome, alternatives to warfarin with similar (or better) efficacy. This review article provides an overview of the recent progress made, the potential challenges involved and the future of these therapeutic approaches.

Stroke prevention in patients with atrial fibrillation: Is the transcatheter occlusion of left atrial appendage already an alternative to anticoagulation?

Cardiac emboli in patients with atrial fibrillation are one of the major causes of ischemic stroke. Because the vast majority of these cardiac emboli descend from the left atrial appendage (LAA), the therapeutic strategy of percutaneous transcatheter occlusion of the LAA by means of a mechanical implant was a logical consequence. Three different devices have been developed and used in humans: PLAATO, WATCHMAN, and ACP. The PLAATO implant, a “soccer ball” shaped self-expanding nitinol cage has demonstrated stroke prevention capability in small, uncontrolled studies. The WATCHMAN implant, a “half rugby ball” shaped self-expanding nitinol cage, has demonstrated non inferiority compared to warfarin treatment in the randomized, controlled PROTECT AF trial. The ACP implant is also a self-expanding nitinol cage. However, its design is of fundamental difference compared to the other two implants. ACP consists of two parts connected by a short waist, which are an “ice-hockey puck” shaped body for the implant fixation in the appendage wall, and a flexible disc for sealing the appendage ostium. Due to the very flexible connecting waist between the two parts, ACP implant adapts itself to the LAA, which appears in significant individual structural variabilities. The currently unpublished initial experience with ACP in Europe is encouraging. Transcatheter occlusion of the LAA offers an appealing way to reduce the incidence of cardioembolic stroke in patients with atrial fibrillation. However, the concerns about procedural safety and the need for long-term follow up should be addressed before this potentially important technology is deployed widely. The transcatheter occlusion of left atrial appendage, therefore, has the potential to become, but is not yet a real alternative to anticoagulation.

Cardioembolic stroke in atrial fibrillation-rationale for preventive closure of the left atrial appendage

Atrial fibrillation is the most common cardiac arrhythmias, and a major cause of morbidity and mortality due to cardioembolic stroke. The left atrial appendage is the major site of thrombus formation in non-valvular atrial fibrillation. Loss of atrial systole in atrial fibrillation and increased relative risk of associated stroke point strongly toward a role for stasis of blood in left atrial thrombosis, although thrombus formation is multifactorial, and much more than blood flow irregularities are implicated. Oral anticoagulation with vitamin-K-antagonists is currently the most effective prophylaxis for stroke in atrial fibrillation. Unfortunately, this treatment is often contraindicated, particularly in the elderly, in whom risk of stroke is high. Moreover, given the risk of major bleeding, there is reason to be skeptical of the net benefit when warfarin is used in those patients. This work reviews the pathophysiology of cardioembolic stroke and critically spotlights the current status of preventive anticoagulation therapy. Various techniques to exclude the left atrial appendage from circulation were discussed as a considerable alternative for stroke prophylaxis.

Is the left atrial appendage more than a simple appendage?

The left atrial appendage (LAA) is a cardiac structure with unique anatomic and functional features. It is significantly more than a simple chamber appended to the left atrium (LA), differing from the LA in structure, function, and hormonal activity. Unfortunately, it is the source of more than 90% of cardiac-based emboli, particularly in atrial fibrillation, mandating lifelong anticoagulation. Percutaneous LAA exclusion was developed to limit or eliminate cardioembolic events in patients with atrial fibrillation. Benign healing of the appendage occurs without adverse hemodynamic effects, and with no residual surface thrombus or tissue damage. The feasibility of this treatment is now established, suggesting that percutaneous therapy is safe, practical and possibly effective to eliminate the need for anticoagulation and significantly reduce cardioembolic events.

Risk of stroke and thrombus formation from delay incontinence of a PLAATO-device in Friedreich ataxia

We present the case of a 76-year-old female with suspected Friedreich ataxia, in whom leakage and thrombosis of a percutaneously implanted left atrial appendage occluder (PLAATO) was observed 2 years after implantation. Because of late developing leakages and thrombi, regular transesophageal echocardiographic examinations should be carried out in patients with occluded left atrial appendages. In view of these complications and the potential important hemodynamic role of the left atrial appendage, the benefit of its occlusion is questionable, and the indications of PLAATO should be strongly reconsidered.

Success of surgical left atrial appendage closure: assessment by transesophageal echocardiography

OBJECTIVES

We sought to determine which surgical technique of left atrial appendage (LAA) closure is most successful by assessing them with transesophageal echocardiography (TEE).

BACKGROUND

Atrial fibrillation is a risk factor for stroke, with 90% of clots occurring in the LAA. Several surgical techniques of LAA closure are used to theoretically reduce the stroke risk, with varying success rates.

METHODS

A total of 137 of 2,546 patients who underwent surgical LAA closure from 1993 to 2004 had a TEE after surgery. Techniques consisted of either excision or exclusion by sutures or stapling. The TEE measurements included color Doppler flow in the LAA and interrogation for thrombus. Patent LAA, remnant LAA (residual stump >1 cm), or excluded LAA with persistent flow into the LAA were identified as unsuccessful closure.

RESULTS

Of the 137 patients, 52 (38%) underwent excision and 85 (62%) underwent exclusion (73 suture and 12 stapler). Only 55 of 137 (40%) of closures were successful. Successful LAA closure occurred more often with excision (73%) than suture exclusion (23%) and stapler exclusion (0%) (p < 0.001). We found LAA thrombus to be present in 28 of 68 patients (41%) with unsuccessful LAA exclusion versus none with excision. At time of TEE, 6 patients with successful LAA closure (11%) and 12 with unsuccessful closure (15%) had evidence of stroke/transient ischemic attack (p = 0.61).

CONCLUSIONS

There is a high occurrence of unsuccessful surgical LAA closure. Of the various techniques, excision appears to be the most successful.

Impact of beating heart left atrial ablation on left-sided heart mechanics

OBJECTIVE

The cut-and-sew Cox-Maze procedure is the gold standard for surgical treatment of atrial fibrillation, but it is associated with long-term impairment of left atrial mechanical function. We developed a bipolar, irrigated radiofrequency ablation device. We hypothesized that beating heart radiofrequency left atrial ablation would result in minimal acute changes in left atrial hemodynamics.

METHODS

Six healthy subjects were studied. Combination pressure-conductance catheters were inserted into the left atrium and ventricle. With the use of the device, atrial ablation was performed on the beating heart without cardiopulmonary bypass, including electrical isolation of the posterior left atrium and atrial appendage myocardium. Simultaneous left-sided heart pressure-volume and intracardiac echocardiography data were acquired before ablation, after left atrial appendage ablation alone, and after all ablation (with and without appendage occlusion). The derived indices of left-sided heart mechanical function were examined.

RESULTS

Relative to baseline, no significant diminishment in pressure-volume or intracardiac echocardiography-derived indices of global left-sided heart mechanical function were observed after ablation, with or without appendage occlusion. Mitral valve morphology and function were not significantly altered. A significant diminishment of atrial appendage systolic flow was noted after appendage ablation in association with spontaneous echocardiographic contrast in this region.

CONCLUSIONS

In this model, ablation does not seem to compromise global left-sided heart mechanical function. However, these findings mask regional diminishment in atrial appendage systolic function. This observation demonstrates that electrical isolation of the appendage should be accompanied by its occlusion or excision. Appendage occlusion after ablation does not seem to compromise left-sided heart mechanical function.

WATCHMAN left atrial appendage system for stroke prevention in atrial fibrillation: a percutaneous-device delivery approach

Sick PB, Schuler G, Hauptmann KE et al.: Initial worldwide experience with the WATCHMAN left atrial appendage system for stroke prevention in atrial fibrillation. J. Am. Coll. Cardiol. 49(13), 1490-1495 (2007). Left atrium appendage (LAA) occlusion is a potential alternative to warfarin in patients with atrial fibrillation who have contraindications to anticoagulation. Currently, there are two devices specifically designed for LAA occlusion: the percutaneous LAA transcatheter occlusion (PLAATO System, ev3 Inc., MN, USA) and the WATCHMAN LAA system (Atritech Inc., MN, USA). Initial results from a study with the WATCHMAN device suggest that the LAA occlusion may reduce the long-term risk for stroke. Available data are still very limited and although occluding the LAA appears to be technically feasible, its long-term safety and ability to reduce stroke incidence remains to be proven. Only prospective randomized studies will be able to tell us if the LAA occlusion devices can be used as an alternative treatment strategy to the standard long-term anticoagulation.