Left Atrial Appendage

Anatomical description of malformations of the neck of the left atrial appendage

The recently-described left atrial appendage (LAA) neck is a truncated cone-shaped structure that connects the LAA orifice to its lobe. It shows malformations in some cases, but their exact description and clinical significance are unknown. Therefore, the aim of this study was to provide a detailed anatomical and morphometric analysis of LAA neck malformations in clinical context. A total of 250 autopsied human hearts (20.0% women, 46.7 ± 18.2 years old) were examined for mural malformations: spikes and bulges. Endocardial roughness of the LAA neck with a depth <2 mm and no recognizable epicardial protrusion was defined as ectopic trabeculation. LAA neck malformations were found in 13.6%, bulges in 10.0% of the hearts examined, spikes in only 3.2%, and ectopic trabeculations in 24.8%. In one case, both a bulge and a spike were found in the LAA neck. Most LAA neck roughness was observed on the aortic and venous surfaces of the LAA neck. Those surfaces were the most common locations for malformations and ectopic trabeculations. The LAA wall was significantly thinner than the surrounding neck wall within the bulges and the ectopic trabeculations, but not in the spikes.

In-Hospital Outcomes of Left Atrial Appendage Occlusion Among Cancer Patients with Atrial Fibrillation: A Nationwide U.S. Study

Background: Atrial fibrillation (AF) is frequently observed in cancer patients, driven by mutual comorbidities and increasing the risk of thromboembolic events. Impediments can hinder the utilization of anticoagulants among patients with malignancy-drug interactions with chemotherapy, renal dysfunction, drug intolerance, and increased bleeding risk. Left atrial appendage occlusion (LAAO) is an effective and safe non-pharmacological approach to prevent thromboembolic complications when anticoagulants are not suitable. Cancer patients were generally excluded from the original LAAO trials, and current safety and efficacy in cancer patients remain uncertain. Methods: This retrospective study utilized the National Inpatient Sample (NIS) database to analyze in-hospital outcomes of LAAO in US patients with and without cancer between 2016 and 2019. Patient demographics, comorbidities, procedures, and in-hospital outcomes were extracted using ICD-10-CM codes. Results: Among 12,273 hospitalizations for LAAO across the US representing an estimated 61,365 LAAO procedures, 2.2% (1365 cases) were performed in cancer patients. Older age, male gender, chronic kidney disease, prior stroke, and anemia were more prevalent in the cancer group, with 785 (58%) having a solid malignancy and 580 (42%) having a hematologic malignancy. Compared to non-cancer patients, cancer patients exhibited a higher rate of in-hospital complications (8.8% vs. 5.7%; p < 0.001), primarily driven by acute kidney injury (4.4% vs. 2.4%; p = 0.002), acute heart failure (3.7% vs. 2.6%; p = 0.012), and cardiac tamponade (1.5% vs. 0.8%; p = 0.006). No significant differences were observed in vascular complications, periprocedural stroke, or in-hospital mortality. Average length of stay (LOS) was longer in cancer patients (1.4 ± 2.7 days vs. 1.8 ± 2.5 days; p < 0.001). Conclusions: This nationwide study found that cancer patients undergoing LAAO had an increased rate of in-hospital complications, particularly acute kidney injury, heart failure, and tamponade, but no increase in in-hospital mortality was observed. Further research is needed to evaluate the long-term safety and efficacy of LAAO for managing embolic prevention in this complex patient population.

State of the Art in Left Atrial Appendage Occlusion

Left atrial appendage occlusion (LAAO) has become an important therapeutic target for stroke prevention in patients with nonvalvular atrial fibrillation. Over the past 2 decades, several advancements in LAAO devices (percutaneous and surgical) have been made for stroke prevention and arrhythmia therapy. However, there are several unanswered questions regarding optimal patient selection, the preferred LAAO approach and device, the management of periprocedural and postprocedural complications, including pericardial effusion, device-related thrombus, and device leaks. This review focuses on fundamental foundational concepts in various aspects of the left atrial appendage and management strategies as they relate to current clinical needs.

First-in-Human Percutaneous Epicardial-Only Left Atrial Appendage Closure Using Sierra Left Atrial Appendage Ligation System

Background: In patients with atrial fibrillation and contraindications for oral anticoagulation, in which an increased risk of stroke remains, a left atrial appendage exclusion should be considered for elimination, because the left atrial appendage is the most common site of thrombus. The aim of this study is to present the first-in-human study results of the Sierra Aegis Left Atrial Appendage Ligation System, a new epicardial-only left atrial appendage closure system. Methods: This study was a prospective, first-in-human, single-center study evaluating the effectiveness and safety of the Sierra Aegis Left Atrial Appendage Ligation System device for epicardial left atrial appendage closure. Seven patients (mean age: 57.3 ± 10.6 years, 71.4% male) were qualified for a left atrial appendage closure because of an increased risk of bleeding with the need for lifelong anticoagulation pharmacology due to an increased risk of stroke. The patients' preoperative and intraoperative characteristics were collected. Patients were observed during their 1-month, 3-month, 6-month, and 1-year follow-up. Results: The mean procedure time was 21.2 ± 8.2 min. All patients spent 3 days in the hospital including monitoring, the performance of preoperative CT scans, and anatomical evaluation. No tamponade, bleeding, thrombus, or left atrial appendage leakage were observed during the procedure or in-hospital stay. During the 1-month, 3-month, 6-month, and 1-year follow-up visits, none of the patients reported any complications. No tamponade, leakage, or left atrial appendage thrombus were observed. Conclusions: This first-in-human study regarding Sierra use for left atrial appendage closure shows promising results regarding the effectiveness and safety of the Sierra device for use in humans.

Right juxtaposition of left atrial appendage combined with multiple cardiac malformations: A case report and review of literature

BACKGROUND

Juxtaposition of the atrial appendages is an extremely rare congenital cardiac malformation. It is usually discovered incidentally during autopsy or surgery. This report aims to increase awareness of right juxtaposition of the left atrial appendage.

CASE PRESENTATION

We report a Chinese Han female aged 2 years and 10 months with recurrent lung infections after birth, who was diagnosed with congenital heart disease, corrected transposition of the great arteries, ventricular septal defect, and arterial ductus arteriosus at the local hospital and improved after the pulmonary artery banding procedure. The patient presented to our hospital with intermittent cough. During preoperative evaluation, a review of imaging data revealed a right juxtaposition of the left atrial appendage on enhanced computed tomography.

CONCLUSION

Right juxtaposition of the left atrial appendage is a rare congenital heart anomaly that often occurs in conjunction with complex cardiac malformations. Diagnosis requires a combination of imaging modalities to improve detection rates. Careful identification of cardiac structures during surgery is crucial, as alterations in cardiac anatomy may increase surgical risks. For instance, the opening of juxtaposed atrial appendages could be mistaken for an atrial septal defect.

Device-Assisted Left Atrial Appendage Exclusion: From Basic Sciences to Clinical Applications

Device-assisted left atrial appendage exclusion plays a crucial role in the prevention of fatal ischemic complications in patients with atrial fibrillation and contraindications to anticoagulation treatment. Various devices with different safety profiles and device-related complications are available in daily practice to perform this procedure. In this review, the anatomy, physiology, and functions of the left atrial appendage were detailed, and all available devices used for epicardial and endocardial exclusion of the left atrial appendage and their clinical outcomes were discussed. Future research should aim to further investigate the long-term effects of left atrial appendage exclusion on body homeostasis, blood coagulation, and cardiac function.

[Surgical closure of the left atrial appendage in cardiac surgery: a review article]

Surgical occlusion of the left atrial appendage during cardiac surgery has been shown to significantly reduce the risk of stroke and systemic embolism in patients with atrial fibrillation and is currently a procedure with a high degree of recommendation. As cardiovascular surgeons we have the opportunity to offer this additional impactful surgical procedure, so the objective of this review is to understand its anatomical and surgical principles, in addition to evaluating the evidence that supports its indication.

Concurrent percutaneous left atrial appendage occlusion and catheter ablation for atrial fibrillation: State-of-the-art review

Stroke prevention and symptom control are two integral pillars in atrial fibrillation (AF) management. Percutaneous left atrial appendage occlusion (LAAO) is effective at reducing stroke risk in high-risk patients with AF who cannot tolerate oral anticoagulant therapy, whilst catheter ablation is effective at reducing AF burden and improving quality-of-life in patients who remain symptomatic despite medical therapy. If both procedures are indicated in an individual patient, they have traditionally been performed on separate occasions, due to long cumulative procedural times, itself associated with thromboembolic risk. Recently, with the advancement of procedural techniques, the concept of concurrent LAAO and AF catheter ablation has gained traction. This review summarises the evidence for and against concurrent LAAO and AF catheter ablation, discussing procedural considerations, including procedural sequencing and post-procedural antithrombotic therapy, safety and efficacy outcomes, and future directions in the field.

Comparison of left atrial appendage measurements between conventional transesophageal echocardiography and "Virtual TEE" reconstructed from computed tomography for pre-procedural planning of device closure

For pre-procedural planning of left atrial appendage (LAA) closure, sizing is crucial. Although transesophageal echocardiography (TEE) is a standard modality, cardiac computed tomography (CT) is also widely used. The virtual TEE (V-TEE) that our group developed enables us to reconstruct images similar to TEE images from CT images. The software should be helpful to understand and plan the procedure strategy. Accordingly, we investigated the utility of V-TEE. Sixty-six patients at 4 participating sites who completed both CT and TEE prior to LAA closure were included. The LAA diameter at the landing zone (LZ) for WATCHMAN™ device implantation was statistically compared at 0°, 45°, 90°, and 135° between V-TEE and TEE. Among 66 cases, only 3 cases were excluded due to poor imaging quality, and 63 cases were analyzed. The device LZ diameters based on V-TEE were strongly correlated with those based on TEE, despite the significantly greater diameter based on V-TEE with mean differences of 2.4 to 3.0 mm (all of them: P < 0.001). The discordances (V-TEE/TEE ratio) at most angles were significantly larger in the elliptical LAAs. V-TEE provides a valuable method for the evaluation of the LAA diameters. V-TEE-based measurements were larger than conventional TEE-based measurements, especially in cases of elliptical LAAs. The assessment by V-TEE has the potential benefit of ensuring proper device sizing regardless of the LAA morphology.

Left atrial appendage closure in conjunction with radiofrequency ablation: Effects on left atrial functioning in patients with paroxysmal atrial fibrillation

Objective

In the present study, we investigated the impact of left atrial appendage closure (LAAC) following catheter ablation (CA) on the left atrial structure and functioning of patients with paroxysmal atrial fibrillation (AF).

Methods

Patients with paroxysmal AF were enrolled in this single-center prospective cohort study between April 2015 and July 2021; 353 patients received CA alone, while 93 patients received CA in combination with Watchman LAAC. We used age, gender, CHA2DS2-VASc, and HAS-BLED scores as well as other demographic variables to perform propensity score matching. Patients with paroxysmal AF were randomly assigned to the CA combined with Watchman LAAC group (combined treatment group) and the simple CA group, with 89 patients in each group. The left atrial structure, reserve, ventricular diastole, and pump functions and their changes in patients were assessed using routine Doppler echocardiography and 2D speckle tracking echocardiography over the course of a 1-year follow-up.

Results

At 1-week follow-up, the reserve, ventricular diastole, and pump functions of the left atrium (LA) increased in both groups; these functions were gradually restored at the 1- to 3-month follow-up; they were close to or returned to their pre-operative levels at the 3-month follow-up; and no significant differences were found compared with the pre-operative levels at the 12-month follow-up. In the first 3 months, the reserve (Ƹ, SRs) and pump functions (SRa) in the combined treatment group decreased significantly when compared with the simple CA group, and the differences were statistically significant.

Conclusion

Patients with paroxysmal AF may experience a short term, partial effect of LAAC on LA reserve and pump functions, which are gradually restored and the effect disappears by 12 months.

Use of Computed Tomography for Left Atrial Appendage Occlusion Procedure Planning and Post-Procedure Assessment

Transcatheter left atrial appendage occlusion (LAAO) is an alternative to systemic anticoagulation in patients with non-valvular atrial fibrillation with increased risk for thromboembolic events. Pre- and post-procedural imaging is essential for technical success, allowing practitioners to identify contraindications, select appropriate devices, and recognize procedural complications. Although transesophageal echocardiography has traditionally served as the preeminent imaging modality in LAAO, cardiac computed tomography imaging has emerged as a noninvasive surrogate given its excellent isotropic spatial resolution, multiplanar reconstruction capability, rapid temporal resolution, and large field of view.

The Left Atrial Appendage and Atrial Fibrillation-A Contemporary Review

In patients with atrial fibrillation, the left atrial appendage may serve as the site of thrombus formation due to stasis that occurs within the appendage because of its shape and trabeculations. Although thrombus formation can be reduced by using anticoagulants, this may be contraindicated in some patients. The need for a better alternative treatment prompted the study of left atrial appendage occlusion for thromboembolism prophylaxis. Due to this, procedures that excise or occlude the left atrial appendage have gained attention because of their ability to prevent thromboembolic events. This article provides a comprehensive review of the left atrial appendage and its associated procedures' clinical utility.

A highly-detailed anatomical study of left atrial auricle as revealed by in-vivo computed tomography

The left atrial auricle (LAA) is the main source of intracardiac thrombi, which contribute significantly to the total number of stroke cases. It is also considered a major site of origin for atrial fibrillation in patients undergoing ablation procedures. The LAA is known to have a high degree of morphological variability, with shape and structure identified as important contributors to thrombus formation. A detailed understanding of LAA form, dimension, and function is crucial for radiologists, cardiologists, and cardiac surgeons. This review describes the normal anatomy of the LAA as visualized through multiple imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI), and echocardiography. Special emphasis is devoted to a discussion on how the morphological characteristics of the LAA are closely related to the likelihood of developing LAA thrombi, including insights into LAA embryology.

Sarcomeric network analysis of ex vivo cultivated human atrial appendage tissue using super-resolution microscopy

Investigating native human cardiac tissue with preserved 3D macro- and microarchitecture is fundamental for clinical and basic research. Unfortunately, the low accessibility of the human myocardium continues to limit scientific progress. To overcome this issue, utilizing atrial appendages of the human heart may become highly beneficial. Atrial appendages are often removed during open-heart surgery and can be preserved ex vivo as living tissue with varying durability depending on the culture method. In this study, we prepared living thin myocardial slices from left atrial appendages that were cultured using an air-liquid interface system for overall 10 days. Metabolic activity of the cultured slices was assessed using a conventional methyl thiazolyl tetrazolium (MTT) assay. To monitor the structural integrity of cardiomyocytes within the tissue, we implemented our recently described super-resolution microscopy approach that allows both qualitative and quantitative in-depth evaluation of sarcomere network based on parameters such as overall sarcomere content, filament size and orientation. Additionally, expression of mRNAs coding for key structural and functional proteins was analyzed by real-time reverse transcription polymerase chain reaction (qRT-PCR). Our findings demonstrate highly significant disassembly of contractile apparatus represented by degradation of [Formula: see text]-actinin filaments detected after three days in culture, while metabolic activity was constantly rising and remained high for up to seven days. However, gene expression of crucial cardiac markers strongly decreased after the first day in culture indicating an early destructive response to ex vivo conditions. Therefore, we suggest static cultivation of living myocardial slices derived from left atrial appendage and prepared according to our protocol only for short-termed experiments (e.g. medicinal drug testing), while introduction of electro-mechanical stimulation protocols may offer the possibility for long-term integrity of such constructs.

The Double-Orifice Left Atrial Appendage: Multimodality and Virtual Transillumination Imaging

•LAA membranes are exceedingly rare with variable morphologies. •Thromboembolic risk with LAA membranes remains unknown. •Use of 3D TEE transillumination may assist in visualization and understanding.

Phasic Diastolic Coronary Artery Compression: A Rare Cause of Chest Pain at Rest

Phasic diastolic coronary artery compression (PDCAC) is a rare phenomenon caused by the compression of a coronary artery between expanding myocardium and a non-compliant overlying structure. We report a unique case of an elderly female who presented with recurrent paradoxical substernal chest pain at rest caused by PDCAC of the proximal left circumflex artery (LCx). Her chest pain likely occurred at rest due to longer diastolic compression time at slower heart rates. Pericardial adhesion secondary to past breast radiation was the likely cause of PDCAC. She was treated successfully with oral anti-hypertensive and anti-anginal medical therapy. PDCAC is a rare phenomenon but should be on the differential for chest pain occurring at rest, especially if there is a history of mediastinal or cardiac radiation or inflammation. PDCAC treatment depends on the underlying cause but can be treated successfully with medical therapy alone.

Congenital absence of left atrial appendage in a patient with ischemic stroke and atrial fibrillation

Left atrial appendage (LAA) is a finger-like muscular extension of the left atrium, and it is the most prominent site for cardiac thrombus in patients with atrial fibrillation. Congenital absence of LAA could be incidentally detected in patient with ischemic stroke and atrial fibrillation. Although it is considered to be an extremely rare cardiac anomaly, its clinical significance remains unknown and there is no clear consensus in the management strategy in those patients. Therefore, we report a case of an incidentally noted congenital absence of LAA in a 68-year-old woman being planned for LAA closure.

Adversarial-based latent space alignment network for left atrial appendage segmentation in transesophageal echocardiography images

Left atrial appendage (LAA) is a leading cause of atrial fibrillation and thrombosis in cardiovascular disease. Clinicians can rely on LAA occlusion (LAAO) to effectively prevent and treat ischaemic strokes attributed to the LAA. The correct selection of the LAAO is one of the most critical stages in the successful surgical process, which relies on the quantification of the anatomical structure of the LAA for successful intervention in LAAO. In this paper, we propose an adversarial-based latent space alignment framework for LAA segmentation in transesophageal echocardiography (TEE) images by introducing prior knowledge from the label. The proposed method consists of an LAA segmentation network, a label reconstruction network, and a latent space alignment loss. To be specific, we first employ ConvNeXt as the backbone of the segmentation and reconstruction network to enhance the feature extraction capability of the encoder. The label reconstruction network then encodes the prior shape features from the LAA labels to the latent space. The latent space alignment loss consists of the adversarial-based alignment and the contrast learning losses. It can motivate the segmentation network to learn the prior shape features of the labels, thus improving the accuracy of LAA edge segmentation. The proposed method was evaluated on a TEE dataset including 1,783 images and the experimental results showed that the proposed method outperformed other state-of-the-art LAA segmentation methods with Dice coefficient, AUC, ACC, G-mean, and Kappa of 0.831, 0.917, 0.989, 0.911, and 0.825, respectively.

Left Atrial Appendage Aneurysm: A Case Report

Left atrial appendage aneurysm (LAAA) is a rare heart anomaly caused by congenital dysplasia of the pectinate muscle or by an acquired pathological condition of the mitral valve or cardiac muscle. It is often incidentally discovered during chest CT or echocardiography as an abnormal dilatation of the LAA. LAAA is associated with life-threatening complications and most patients require surgical treatment. Therefore, it is important to evaluate associated complications as well as precise diagnoses. This report presents the case of a surgically confirmed LAAA in a 53-year-old female. We also discuss the pathophysiology of LAAA and significant findings related to mortality that can be detected on CT and MRI.

Left Atrial Appendage Thrombosis and Oral Anticoagulants: A Meta-Analysis of Risk and Treatment Response

Background: Left atrial appendage thrombus (LAAT) is the main cause of cardioembolism in patients with nonvalvular atrial fibrillation (AF). Emerging evidence indicates that direct oral anticoagulants (DOACs) may be a preferred, safer choice for patients with LAAT. However, current guidelines indicate vitamin K antagonist (VKA) as the preferred treatment for LAAT. We conducted a meta-analysis to compare the efficacy of VKA and DOAC for the treatment of LAAT. Methods: The search was conducted in the PubMed, Embase, Google Scholar, and Cochrane Library databases from inception to July 2022, with the language restricted to English. A first analysis was conducted to evaluate the risk of LAAT under VKA or DOAC treatment. A second analysis was conducted to compare the resolution of LAAT under VKA and DOAC treatment. Results: In 13 studies comparing LAAT incidence rates under VKA and DOAC treatment, significant superiority of DOAC was detected (pooled RR = 0.65, 95% CI = 0.47-0.90, p = 0.009) with moderate heterogeneity being identified in the pooled studies. In 13 studies comparing LAAT resolution under VKA and DOAC use, treatment with DOAC exhibited a significantly increased probability of LAAT resolution compared with VKA (pooled odds ratio = 1.52, 95% CI = 1.02-2.26, p = 0.040). Conclusions: This meta-analysis suggests a superiority of DOAC over VKA with respect to LAAT incidence in people with AF and the likelihood of LAAT resolution. Due to their established safety profile, DOAC is a preferable choice for anticoagulation, although further randomized controlled studies are warranted to provide further evidence of their suitability as a new recommended treatment.

Computed tomography-based selection of transseptal puncture site for percutaneous left atrial appendage closure

BACKGROUND

An inferoposterior transseptal puncture (TSP) is generally recommended for percutaneous left atrial appendage (LAA) closure. However, the LAA is a highly variable anatomical structure. This may have an impact on the preferred TSP site.

AIMS

This study aimed to determine the optimal TSP site for percutaneous LAA closure in different LAA morphologies.

METHODS

In this prospective study, 182 patients undergoing percutaneous LAA closure were included. The spatial relationship of the LAA to the fossa ovalis and its consequence for TSP was assessed at preprocedural cardiac computed tomography (CCT).

RESULTS

Based on CCT analysis, it was predicted that coaxial alignment between the delivery sheath and the LAA would be obtained by an inferoposterior, inferocentral, or inferoanterior TSP in 75%, 16% and 8% of cases, respectively. This was also confirmed by procedural LAA angiogram in 175 cases (96%) with <30° angle between the delivery sheath and the LAA central axis. Multivariate logistic regression analysis identified reverse chicken wing LAA (odds ratio [OR] 6.36 [1.85-29.3]; p=0.005) and posterior bending of the proximal LAA (OR 17.2 [3.3-96.2]; p<0.001) as independent predictors of a central or anterior TSP - this to increase the chance of obtaining coaxial alignment between the delivery sheath and the LAA.

CONCLUSIONS

An inferoposterior TSP is recommended in the majority of percutaneous LAA closure procedures in order to obtain coaxial alignment between the delivery sheath and the LAA. An inferior but more central/anterior TSP should be recommended in case of a reverse chicken wing LAA or posterior bending of the proximal LAA, which occurs in 20-25% of cases.

Association Between Left Atrial Appendage Morphology and Function and the Risk of Ischaemic Stroke in Patients with Atrial Fibrillation

AF is the most common cardiac arrhythmia and has been identified as an independent risk factor for stroke. The European Society of Cardiology guidelines recommend a thromboembolic event risk assessment based on the CHA₂DS₂-VASc score. However, stroke also occurs in some patients with a low CHA₂DS₂-VASc score. Therefore, it is necessary to find new factors to improve thromboembolic risk stratification in AF patients. Over 90% of embolic strokes are caused by thrombi originating from the left atrial appendage (LAA). Thus, certain anatomical or functional parameters of the LAA could potentially be used to predict cardioembolic stroke. Studies have suggested that some of these factors, such as LAA morphology, number of LAA lobes, LAA dimensions, LAA volume, distance from the LAA ostium to the first bend of LAA, LAA orifice diameter, extent of LAA trabeculations, LAA takeoff, LAA flow velocity and LAA strain rate, are independently associated with a higher risk of stroke in a population of patients with AF and improve the performance of the CHA₂DS₂-VASc score. However, the results are conflicting and, so far, no new parameter has been added to the CHA₂DS₂-VASc score.

Left atrial appendage occlusion in a mirror-image dextrocardia: A case report and review of literature

BACKGROUND

In mirror-image dextrocardia, the anterior-posterior position of the cardiac chambers and great vessels is maintained, but the left-right orientation of the abdominal organs is reversed. The abnormal anatomy of the heart poses surgical challenges and problems in dealing with surgical risk and monitoring complications. There are few reports on closure of the left atrial appendage (LAA) in dextrocardia and no reports on the application of enhanced recovery after surgery (ERAS) following LAA occlusion (LAAO) procedures.

CASE SUMMARY

The objective for this case was to ensure perioperative safety and accelerate postoperative recovery from LAAO in a patient with mirror-image dextrocardia. ERAS was guided by the theory and practice of nursing care. Atrial fibrillation was diagnosed in a 77-year-old male patient, in whom LAAO was performed. The 2019 guidelines for perioperative care after cardiac surgery recommend that the clinical nursing procedures for patients with LAAO should be optimized to reduce the incidence of perioperative complications and ensure patient safety. Music therapy can be used throughout perioperative treatment and nursing to improve the anxiety symptoms of patients.

CONCLUSION

The procedure was uneventful and proceeded without complications. Anxiety symptoms were improved.

Prevalence of left atrial appendage thrombus in patients with acute ischaemic stroke and sinus rhythm: a cross-sectional study

OBJECTIVE

Thrombi originating in the left atrial appendage (LAA) mainly form because of atrial fibrillation (AF) and are a known cause of cardioembolic stroke. We aimed to investigate the prevalence of LAA thrombus in patients with acute ischaemic stroke (AIS) and sinus rhythm on 12-lead ECG.

METHODS

From June 2019 to February 2021, we conducted a cross-sectional study wherein we performed transoesophageal echocardiography (TEE) in patients with AIS and sinus rhythm on 12-lead ECG who were referred for detection of LAA thrombus. After TEE, all patients underwent 24-hour ECG monitoring to screen for paroxysmal AF. Predictors of LAA thrombus were determined using logistic regression analysis.

RESULTS

Overall, 223 patients (age: 66.2±11.3 years, men: 61.4%) were included in the study. LAA thrombus was detected in 15 patients (6.7%). Paroxysmal AF was detected in 14 of the 15 patients during 24-hour ECG monitoring. Compared with the non-thrombus group, the thrombus group had a statistically significant higher rate of spontaneous echo contrast (SEC), longer LAA, lower peak LAA emptying velocity and predominantly bilateral stroke. In the adjusted model, the presence of SEC increased the probability of LAA thrombus (OR 9.04; 95% CI 2.12 to 38.54; p=0.003).

CONCLUSIONS

In patients with AIS and sinus rhythm on 12-lead ECG, our study revealed that the prevalence of LAA thrombus was 6.7% with the most prevalent aetiology being paroxysmal AF. The presence of SEC can be a predictor of LAA thrombus in these patients.

Analysis of outcome of 6-month readmissions after percutaneous left atrial appendage occlusion

OBJECTIVE

Percutaneous left atrial appendage occlusion (LAAO) is an alternative strategy for prevention of thromboembolic events in patients with atrial fibrillation and unsuitable for long-term oral anticoagulation. The study aimed to evaluate the causes and timing of readmissions within 6 months following percutaneous LAAO in a real-world setting.

METHODS

We conducted a retrospective cohort study of percutaneous LAAO performed in the USA between January and June of 2016-2018 using the Nationwide Readmissions Database.

RESULTS

Overall, 12 446 patients who underwent LAAO were included in the analyses and 3477 patients (28%) were readmitted within 6 months following the interventions. Readmitted patients were more often women (p=0.001). The index hospitalisation was characterised by longer duration of hospital stay (p<0.001) and complicated with acute kidney injury (p<0.001) among readmitted patients compared with those without readmissions. Readmissions within 6 months following the index intervention were mainly due to heart failure (13%) and gastrointestinal bleeding (12%). Characteristics associated with readmissions due to heart failure included previously known heart failure (HR 2.39; 95% CI 1.70 to 3.37), valvular heart disease (HR 1.39; 95% CI 1.05 to 1.84) and chronic kidney disease (HR 1.42; 95% CI 1.03 to 1.94). Readmissions due to gastrointestinal bleeding were associated with diabetes mellitus (HR 1.78; 95% CI 1.25 to 2.53), chronic kidney disease (HR 1.86; 95% CI 1.23 to 2.81) and previous anaemia (HR 2.41; 95% CI 1.54 to 3.77).

CONCLUSIONS

After percutaneous LAAO, over a quarter of the patients in the USA required rehospitalisation within 6 months, mainly due to heart failure and gastrointestinal bleeding.

Left Atrial Remodeling and Brain Natriuretic Peptide Levels Variation after Left Atrial Appendage Occlusion

Background: Few data are available about brain natriuretic peptide (BNP) variation and left atrial remodeling after the left atrial appendage occlusion (LAAO) technique. Methods: Prospective study included all consecutive patients successfully implanted with an LAAO device. Contrast-enhanced cardiac computed tomography (CT) was performed before and 6 weeks after the procedure with reverse left atrial remodeling defined by an increase in LA volume >10%, together with blood sampling obtained before, 48 h after device implantation and at the first visit after discharge (30–45 days) for BNP measurement. Results: Among the 43 patients implanted with a complete dataset, mean end-diastolic LA volume was 139 ± 64 mL and 141 ± 62 mL at baseline and during follow-up (45 ± 15 days), respectively, showing no statistical difference (p = 0.45). No thrombus was seen on the atrial side of the device. Peridevice leaks (defined as presence of dye in the LAA beyond the device) were observed in 17 patients (40%) but were trivial or mild. Reverse atrial remodeling (RAR) at 6 weeks was observed in six patients (14%). Despite no difference in BNP levels on admission, median BNP levels at 48 h were slightly increased in RAR patients when compared with controls. During FU, BNP levels were strictly identical in both groups. These results were not modified even when each RAR case was matched with two controls on age, LVEF, creatinine levels and ACE inhibitors treatment to avoid potential confounders. Conclusion: Our study showed that despite the fact that the LAAO technique can induce left atrial remodeling measured by a CT scan, it does not seem to impact BNP levels on the follow-up. The results need to be transposed to clinical outcomes of this expanding population in future studies.

Role of the Left Atrial Appendage in Systemic Homeostasis, Arrhythmogenesis, and Beyond

The left atrial appendage (LAA) affects body homeostasis via atrial natriuretic peptide and the renin-angiotensin-aldosterone system and plays an important role in atrial compliance. Approximately 90% of clots in nonvalvular atrial fibrillation (AF) are formed in the LAA. AF is the most common sustained cardiac arrhythmia and is frequently associated with stroke. Because anticoagulation for stroke prophylaxis carries a higher bleeding risk, LAA closure via epicardial and endocardial approaches has gained popularity and is being increasingly pursued for arrhythmogenic, homeostatic, and stroke-reduction benefits. This review discusses the homeostatic role of the LAA and its involvement in arrhythmogenesis and thrombus formation.

The use of cardiac computed tomography angiography in the assessment of percutaneous left atrial appendage closure - Review and experts recommendations endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle

Atrial fibrillation is the most common cause of arrhythmia which is responsible for over 15% of ischemic strokes, most of these being secondary to migration of a left atrial appendage (LAA) thrombus. In patient with contraindication to anticoagulant therapy, percutaneous closure system placement may be indicated. Cardiac computed tomography (CT) angiography plays a central role in the initial assessment as well as in the follow-up. The purpose of the pre-implantation cardiac CT angiography is to evaluate the anatomy of the LAA in order to select the most suitable prosthesis and check for any contraindication to device implantation. Image analysis is divided into four steps that include analysis of the approach; search for a thrombus in the LAA; investigation of the anatomy of the LAA (morphology of the LAA, dimensions of the LAA and choice of device) and cardiac and thoracic assessments. Follow-up involves CT examination to check for correct placement of the device and to detect any complications. On the basis of the results of currently available published research, a panel of experts has issued recommendations regarding cardiac CT angiography prior to percutaneous LAA closure device placement, which were further endorsed by the Société française d'imagerie cardiaque et vasculaire diagnostique et interventionnelle (SFICV).

Pre- and Postprocedural CT of Transcatheter Left Atrial Appendage Closure Devices

Transcatheter left atrial appendage (LAA) closure is an alternative to long-term anticoagulation therapy in selected patients with nonvalvular atrial fibrillation who have an increased risk for stroke. LAA closure devices can be implanted by means of either an endocardial or a combined endocardial and epicardial approach. Preprocedural imaging is key to identifying contraindications, accurately sizing the device, and minimizing complications. Transesophageal echocardiography (TEE) has been the reference standard imaging modality to assess the anatomy for LAA closure and to provide intraprocedural guidance. However, CT has emerged as a less-invasive alternative to TEE for pre- and postprocedural imaging. CT is comparable to TEE for exclusion of thrombus but is superior to TEE for the delineation of complex LAA anatomy, measurement for device sizing, and evaluation of pulmonary venous and extracardiac structures. CT provides accurate measurements of the LAA ostial diameter, landing zone diameter, and LAA length, which are vital for accurate sizing of the device. CT allows evaluation of the relationship with the pulmonary veins and other adjacent structures that can be injured during the procedure. CT also simulates procedural fluoroscopic angles and provides evaluation of the interatrial septum, which is punctured during LAA closure. CT also provides a more convenient method for the evaluation of postprocedural complications such as incomplete closure, peridevice leaking, device-related thrombus, and device dislodgement. Online supplemental material is available for this article. ^©RSNA, 2021.

Morphology of the Left Atrial Appendage: Introduction of a New Simplified Shape-Based Classification System

BACKGROUND

The left atrial appendage (LAA) is a heart structure with known prothrombogenic and pro-arrhythmogenic properties.

AIM

The aim of this study was to evaluate the specific anatomy of the LAA and to create a simple classification system based on the shape of its body.

METHOD AND RESULTS

This study investigated 200 randomly selected autopsied human hearts (25.0% females, 46.6±19.1 years old). Three (3) types of LAAs were distinguished: the cauliflower type (no bend, limited overall length, compact structure [36.5%]); the chicken wing type (substantial bend in the dominant lobe [37.5%]), and the arrowhead type (no bend, one dominant lobe of substantial length [26.0%]). Additional accessory lobes were present in 55.5% of all LAAs. Significant variations between category types were noted in LAA length (chicken wing: 35.7±9.8 mm, arrowhead: 30.8±10.1 mm, cauliflower: 22.3±9.6 mm [p<0.001]) and in the thickness of pectinate muscles located within the LAA apex (arrowhead: 1.2±0.7 mm; cauliflower: 1.1±0.6 mm; chicken wing: 0.9±0.6 mm [p<0.001]). Left atrial appendage volume and orifice size were not affected by the type of LAA shape. The age of the donor was positively correlated with LAA volume (r=0.29, p=0.005), body length (r=0.26, p=0.012), and area of the orifice (r=0.36, p<0.001). Donors with an oval LAA orifice were significantly older than those with round orifices (50.2±16.6 vs 43.7±20.4 years [p=0.014]) and had significantly heavier hearts (458.2±104.8 vs 409.6±114.1g [p=0.002]).

CONCLUSIONS

This study delivered a new simple classification system of the LAA based on its body shape. An increase in age and heart weight was associated with LAA enlargement and a more oval-shaped orifice. Results of current study may help to estimate the different thrombogenic properties associated with each LAA type and be an assistance during planning and performing interventions on LAA.

Right Atrial Thrombosis and Pulmonary Embolism: A Narrative Review

Prompt diagnosis of pulmonary embolism (PE) remains challenging, which often results in a delayed or inappropriate treatment of this life-threatening condition. Mobile thrombus in the right cardiac chambers is a neglected cause of PE. It poses an immediate risk to life and is associated with an unfavorable outcome and high mortality. Thrombus residing in the right atrial appendage (RAA) is an underestimated cause of PE, especially in patients with atrial fibrillation. This article reviews achievements and challenges of detection and management of the right atrial thrombus with emphasis on RAA thrombus. The capabilities of transthoracic and transesophageal echocardiography and advantages of three-dimensional and two-dimensional echocardiography are reviewed. Strengths of cardiac magnetic resonance imaging (CMR), computed tomography, and cardiac ventriculography are summarized. We suggest that a targeted search for RAA thrombus is necessary in high-risk patients with PE and atrial fibrillation using transesophageal echocardiography and/or CMR when available independently on the duration of the disease. High-risk patients may also benefit from transthoracic echocardiography with right parasternal approach. The examination of high-risk patients should involve compression ultrasonography of lower extremity veins along with the above-mentioned technologies. Algorithms for RAA thrombus risk assessment and protocols aimed at identification of patients with RAA thrombosis, who will potentially benefit from treatment, are warranted. The development of treatment protocols specific for the diverse populations of patients with right cardiac thrombosis is important.

Evaluation of Left Atrial Appendage Isolation Using Cardiac MRI after Catheter Ablation of Atrial Fibrillation: Paradox of Appendage Reservoir

Objective

To assess the effect of left atrial appendage (LAA) isolation on LAA emptying and left atrial (LA) function using cardiac MRI in patients who underwent successful catheter ablation of atrial fibrillation (AF).

Materials and Methods

This retrospective study included 84 patients (mean age, 59 ± 10 years; 67 males) who underwent cardiac MRI after successful catheter ablation of AF. According to the electrical activity of LAA after catheter ablation, patients showed either LAA isolation or LAA normal activity. The LAA emptying phase (LAA-EP, in the systolic phase [SP] or diastolic phase), LAA emptying flux (LAA-EF, mL/s), and LA ejection fraction (LAEF, %) were evaluated by cardiac MRI.

Results

Of the 84 patients, 61 (73%) and 23 (27%) patients showed LAA normal activity and LAA isolation, respectively. Incidence of LAA emptying in SP was significantly higher in LAA isolation (91% vs. 0%, p < 0.001) than in LAA normal activation. LAA-EF was significantly lower in LAA isolation (40.1 ± 16.2 mL/s vs. 80.2 ± 25.1 mL/s, p < 0.001) than in LAA normal activity. Furthermore, LAEF was significantly lower in LAA isolation (23.7% ± 11.2% vs. 31.1% ± 16.6%, p = 0.04) than in LAA normal activity. Multivariate analysis demonstrated that the LAA-EP was independent from LAEF (p = 0.01).

Conclusion

LAA emptying in SP may be a critical characteristic of LAA isolation, and it may adversely affect the LAEF after catheter ablation of AF.

Successful Percutaneous Left Atrial Appendage Closure in the Presence of a Nonobstructive Appendage Membrane

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LAA membranes are rare and usually diagnosed incidentally on TEE.

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A thorough TEE assessment is needed to distinguish LAA membranes from other entities.

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The clinical significance of LAA membranes and association with stroke are unclear.

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The presence of an LAA membrane may affect placement of an LAA occlusion device.

Epicardial versus Endocardial Closure: Is One Better than the Other?

Left atrial appendage occlusion is an evolving technology with demonstrable benefits of stroke prophylaxis in patients with atrial fibrillation unsuitable for anticoagulation. This has resulted in the development of a plethora of transcatheter devices to achieve epicardial exclusion and endocardial occlusion. In this review, the authors summarize the differences in technique, target patient population, outcomes, and complication profiles of endocardial and epicardial techniques.

Use of Cardiac Computed Tomography and Magnetic Resonance Imaging in Case Management of Atrial Fibrillation with Catheter Ablation

Atrial fibrillation (AF) is the most common arrhythmia associated with the risk of morbidity and mortality in clinical patients. AF is considered as an arrhythmia type that develops and progresses through close connection with cardiac structural arrhythmogenic substrates. Since the introduction of catheter ablation-mediated electrical isolation of arrhythmogenic substrates, cardiac imaging indicates improved treatment outcome and prognosis with appropriate candidate selection, ablation catheter guidance, and post-ablation follow-up. Currently, cardiac computed tomography (CCT) and cardiovascular magnetic resonance (CMR) imaging are essential in the case management of AF at both pre-and post-procedural stages of catheter ablation. In this review, we discuss the roles and technical considerations of CCT and CMR imaging in the management of patients with AF undergoing catheter ablation.

Thromboembolism in Atrial Fibrillation: Role of the Left Atrial Appendage

Atrial fibrillation (AF) is the most common arrhythmia. Patients with AF have a higher risk for thromboembolism than individuals without AF. The left atrial appendage (LAA) is the main source of thromboembolism because of its anatomic, mechanical, and electrophysiologic properties, and accounts for more than 90% of thrombus formation in patients with AF. Advancement in imaging expands knowledge about anatomic and physiologic characteristics of LAA. The risk of thromboembolism events in patients with AF depends on clinical comorbidities and structural and physiologic parameters of atria, especially LAA. This article discusses AF-related thromboembolic events and the role of the LAA.

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.

Animal model of left atrial thrombus in congestive heart failure in rats

The aim of the present study was to develop and study a new model of left atrial thrombus (LAT) in rat with congestive heart failure (CHF). CHF was induced by aortic banding for 2 mo, followed by ischemia-reperfusion (I/R) and subsequent aortic debanding for 1 mo. Cardiac function and the presence of LAT were assessed by echocardiography. Masson's staining was performed for histological analysis. All CHF rats presented with significantly decreased cardiac function, fibrosis in remote myocardium, and pulmonary edema. The incidence rate of LAT was 18.8% in the rats. LAT was associated with severity of aortic constriction, aortic pressure gradient, aortic blood flow velocity, and pulmonary edema but not myocardial infarction or a degree of left ventricular depression. The progressive process of thrombogenesis was characterized by myocyte hypertrophy, fibrosis, and inflammation in the left atrial wall. Fibrin adhesion and clot formation were observed, whereas most LAT presented as a relatively hard "mass," likely attributable to significant fibrosis in the middle and outer layers. Some LAT mass showed focal necrosis as well as fibrin bulging. Most LAT occurred at the upper anterior wall of the left atrial appendage. Aortic debanding had no significant impact on large LATs (>5 mm2) that had formed, whereas small LATs (<5 mm2) regressed 1 mo after aortic release. LAT is found in a rat model of aortic banding plus I/R followed by aortic debanding. The model provides a platform to study molecular mechanisms and potential new pathways for LAT treatment. NEW & NOTEWORTHY It is critically important to have a rodent model to study the molecular mechanism of thrombogenesis in the left atrium. Left atrial thrombus (LAT) is not a simple fibrin clot like those seen in peripheral veins or arteries. Rather, LAT is a cellular mass that likely develops in conjunction with blood clotting. Studying this phenomenon will help us understand congestive heart failure and promote new therapies for LAT.

Dual-Energy Computed Tomography-Enabled Material Separation in Diagnosing Left Atrial Appendage Thrombus

We explored the potential clinical value of material separation enabled by dual-energy spectral computed tomography in detecting left atrial appendage thrombi. The study enrolled 24 patients who were scheduled to undergo atrial fibrillation ablation (12 with and 12 without left atrial appendage thrombi). Computed tomograms were acquired in gemstone spectral imaging mode; the densities in the regions of the left atrial appendage cavities, pectinate muscles, and left atrial appendage thrombi were analyzed on monochromatic 70-keV images. Iodine and blood were chosen as the material basis pair; the iodine and blood densities were observed and quantitatively determined from the iodine- and blood-specific material decomposition images. On the 70-keV monochromatic and iodine-specific images, the left atrial appendage pectinate muscles and thrombi appeared as areas of hypodense attenuation. On the blood-specific images, similar areas of high attenuation were observed in the thrombi and cavities, whereas lower attenuation was noticed in the pectinate muscles. The quantitative iodine and blood densities in the pectinate muscles were lower than those in the cavities (P <0.001). The iodine densities in the thrombi were lower than those in the cavities (P <0.001); however, blood densities did not differ significantly between the thrombi and cavities (P=0.192). Compared with the pectinate muscles, the thrombi showed lower blood-density differences (P=0.003) and higher iodine-density differences (P=0.006) in relation to the cavities. Spectral computed tomography-enabled material separation is a novel method for differentiating left atrial appendage thrombi from pectinate muscles. The potential applications of this technology warrant further studies.

Pro-Arrhythmogenic Effects of Heterogeneous Tissue Curvature - A Suggestion for Role of Left Atrial Appendage in Atrial Fibrillation

BACKGROUND

The arrhythmogenic role of complex atrial morphology has not yet been clearly elucidated. We hypothesized that bumpy tissue geometry can induce action potential duration (APD) dispersion and wavebreak in atrial fibrillation (AF).

METHODS AND RESULTS

We simulated a 2D-bumpy atrial model by varying the degree of bumpiness, and 3D-left atrial (LA) models integrated by LA computed tomographic (CT) images taken from 14 patients with persistent AF. We also analyzed wave-dynamic parameters with bipolar electrograms during AF and compared them with LA-CT geometry in 30 patients with persistent AF. In the 2D-bumpy model, APD dispersion increased (P<0.001) and wavebreak occurred spontaneously when the surface bumpiness was greater, showing phase transition-like behavior (P<0.001). The bumpiness gradient 2D-model showed that spiral wave drifted in the direction of higher bumpiness, and phase singularity (PS) points were mostly located in areas with higher bumpiness. In the 3D-LA model, PS density was higher in the LA appendage (LAA) compared with other parts of the LA (P<0.05). In 30 persistent-AF patients, the surface bumpiness of LAA was 5.8-fold that of other LA parts (P<0.001), and exceeded critical bumpiness to induce wavebreak. Wave dynamics complexity parameters were consistently dominant in the LAA (P<0.001).

CONCLUSIONS

Bumpy tissue geometry promoted APD dispersion, wavebreak, and spiral wave drift in in-silico human atrial tissue, and corresponded to clinical electroanatomical maps.

Left Atrial Appendage Occlusion for Stroke Prevention

More than 2.3 million adults in the United States have atrial fibrillation (AF), which exposes them to a 5-fold increased risk of stroke. The left atrial appendage (LAA) appears to be the source of thrombus formation in the vast majority of these patients. Anticoagulation significantly reduces the risk of stroke, but often we encounter patients who have absolute or relative contraindication to anticoagulation. Percutaneous LAA exclusion offers an alternative to anticoagulation to decrease the risk of stroke. Three device systems are currently available in the United States. The WATCHMAN® device is the most studied and approved by Food and Drug Administration (FDA) to be used in patients with AF unsuitable for anticoagulation who are at a high risk of stroke. The Amulet® device is currently being used as part of the AMPLATZER® Amulet® LAA Occluder trial, which is a non-inferiority randomized trial comparing the Amulet® to the WATCHMAN® device. The third device in use is the LARIAT®, which is an FDA approved snare and pre-tied stich system. It is used to approximate soft tissue which in this case is the LAA. It is a hybrid system and requires both epicardial and endocardial access. The main obstacle to percutaneous LAA closure is procedural related complications, which can be minimized with optimum operator experience.