Echocardiography in Percutaneous Left Atrial Appendage Occlusion and Related Complications

Atrial fibrillation (AF) is a devastating disease with a large global prevalence. The left atrial appendage (LAA) is a major source of thrombi in patients with AF. Echocardiography plays an important role in identifying LAA thrombi and has become an invaluable imaging tool in planning for LAA occlusion (LAAO) in patients intolerant to anticoagulation. This review article will discuss the role of echocardiography in selecting patients for LAAO, intraprocedural monitoring, and identifying procedure-related complications.

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.

How the trabeculae protrude within the left atrial appendage is the key factor affecting thrombosis in patients with atrial fibrillation

The left atrial appendage (LAA) is a major site of thrombosis in patients with non-valvular atrial fibrillation. The myocardial trabeculae within the LAA have a peculiar tendency to protrude but its relationship to thrombosis remains unknown. This study aimed to investigate the relationship between the condition of trabeculae protrusion and LAA thrombosis. This retrospective study consecutively selected patients diagnosed with non-valvular atrial fibrillation and prepared for radiofrequency ablation from January 2011 to May 2020. Patients were divided into the thrombus group (n = 43), the sludge group (n = 35), and the normal group (n = 407) according to whether the thrombus or sludge was present. The trabeculae protruding angle (TPA), which was measured by the CT scans, was used to quantify the trabeculae protrusion condition. Patients' clinical data, TPA, LAA emptying velocity, and other factors were collected and compared among the three groups. A total of 485 patients were enrolled. The range of TPA was between 0 and 158 degrees, with an average of 89.3 ± 35.6 degrees. The TPA was significantly greater in the thrombus (109.3 ± 14.8 degrees) and sludge groups (110.8 ± 12.8 degrees) than in the normal group (85.3 ± 37.1). The incidence of LAA thrombus and sludge increased with increasing TPA. Multivariate regression analysis showed that the TPA was an independent risk factor for LAA thrombus (OR = 1.046, 95%CI: 1.020-1.073, p < 0.001) and sludge (OR = 1.035, 95%CI: 1.017-1.053, p < 0.001). Further analysis revealed that the TPA was negatively correlated with LAA emptying velocity but its effect on promoting thrombosis was not only mediated by slowing down the flow velocity. The TPA can well reflect the condition of trabeculae protrusion. This study revealed that the TPA was an independent risk factor for LAA thrombus or sludge, providing a potential indicator for future thrombosis risk assessment.

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.

Left atrial appendage occlusion after thromboembolic events or left atrial appendage sludge during anticoagulation therapy: Is two better than one? Real-world experience from a tertiary care hospital

BACKGROUND

The role of left atrial appendage occlusion (LAAO) for atrial fibrillation patients that during oral anticoagulant therapy (OAC) suffer from ischemic events or present LAA sludge, and the best postinterventional anticoagulant regimen, need to be defined. We present our experience with a hybrid approach of LAAO+ lifelong OAC therapy in this cohort of patients.

METHODS

Out of 425 patients treated with LAAO, 102 underwent LAAO because, despite OAC, suffered from ischemic events or presented with LAA sludge. Patients without high bleeding risk were discharged with the aim of maintaining lifelong OAC. This cohort was then matched to a population who underwent LAAO in primary ischemic events prevention. The primary endpoint was the composite of all-cause death and major adverse cardiovascular events consisting of ischemic stroke, systemic embolism (SE), and major bleeding.

RESULTS

Procedural success was 98%, and 70% of patients were discharged with anticoagulant therapy. After a median follow-up of 47.2 months, the primary endpoint occurred in 27 patients (26%). At multivariate analyses, coronary artery disease (OR 5.1, CI 1.89-14.27, p = .003) and OAC at discharge (OR 0.29, CI 0.11-0.80, p = .017) were associated with the primary endpoint. After propensity score matching, no significant difference was found in the survival free from the primary endpoint according to the indication for LAAO (p = .19).

CONCLUSIONS

In this high-ischemic risk cohort, LAAO + OAC seem a long-term safe and effective therapeutical approach, with no difference in the survival free from the primary endpoint according to the indication for LAAO in a matched cohort.

Assessment of left atrial appendage function by echocardiography

The left atrial appendage (LAA) is considered not only to be the most frequent site of thrombus formation, but also to play a pivotal role in maintaining normal cardiac function. Transesophageal echocardiography (TEE) is widely used to assess LAA function. The LAA flow velocity has been used as a surrogate for LAA function, and it varies with multiple interrelated factors including age, hemodynamics, type of arrhythmia, and antiarrhythmic interventions. Relatively great importance of LAA function is involved with intraatrial thrombus formation and subsequent thromboembolism, and thus, understanding of characteristics and behaviors of the LAA under various clinical conditions may help determine strategies against atrial thrombosis. Also, techniques other than TEE-derived Doppler to assess LAA function, such as tissue Doppler imaging, have been proposed. In this review, we introduce clinical and echocardiographic correlates of LAA function, the LAA flow velocity in particular, its significance, and how to interpret functional patterns of the LAA each relevant to specific clinical settings.

Cryoballoon Ablation Beyond Pulmonary Vein Isolation in the Setting of Persistent Atrial Fibrillation

INTRODUCTION

Catheter ablation has been demonstrated to be a safe and an effective treatment for drug resistant atrial fibrillation (AF); electrical isolation of pulmonary veins (PVI) is the main strategy in paroxysmal AF, since pulmonary vein triggers have a pivotal role in its pathogenesis; non-paroxysmal AF is a complex arrhythmia that results from the interplay of a substrate, namely AF-induced electrical and structural atrial remodeling, and a trigger that can be often found outside pulmonary veins, namely non-pulmonary veins triggers.

AREAS COVERED

The aim of this review is to provide a state-of-the-art overview of non-pulmonary veins triggers with special focus on cryoballoon (CB) catheter ablation.

EXPERT OPINION

Besides PVI, CB catheter ablation of non-pulmonary veins triggers is a novel and promising strategy for non-paroxysmal AF.

A Prospective Study to Evaluate the Effectiveness of Edoxaban for the Resolution of Left Atrial Thrombosis in Patients with Atrial Fibrillation

Available evidence on left atrial (LA) thrombus dissolution in patients with atrial fibrillation (AF) largely refers to the use of vitamin K antagonist oral anticoagulants (VKAs), showing >50% thrombus resolution over a 4-week to 12-month treatment period. Available data on non-vitamin K antagonist anticoagulants (NOACs) in this setting are limited and derive from isolated case reports or observational small-sized investigations with dabigatran, rivaroxaban or apixaban. The aim of this study was to investigate the extent of thrombus resolution with edoxaban therapy in patients with AF and LA thrombosis. We conducted a prospective, observational, open-label pilot study in seven Italian institutions. We included a total of 25 patients with non-valvular AF and LA (or left atrial appendage (LAA)) thrombosis, documented by transesophageal echocardiography (TEE). All patients received edoxaban OD treatment (n = 23 on 60 mg daily; n = 2 on 30 mg daily) and underwent TEE examination after 4 weeks. The primary endpoint was the percentage of patients with complete thrombus resolution by TEE imaging at 4 weeks. The mean age of the study population was 68.3 ± 10.8 years with a female population of 16%. AF was permanent in all cases, with a mean arrhythmia duration of 4.3 ± 1.7 years. CHA2DS2-VASc and HAS-BLED scores were 3.2 ± 1.5 and 1.9 ± 1.1, respectively. We were able to demonstrate a complete thrombus resolution in 14 patients (56%) at 4 weeks. In patients with residual atrial thrombosis (n = 11), we observed a 15.4 ± 14.9% reduction in the thrombus area from baseline. As compared with patients without thrombus dissolution, those with thrombus resolution had a numerically lower-indexed LA diameter (27.9 ± 9.3 vs 34.8 ± 16.1 mm/m2), a smaller maximum thrombus area at baseline (45.5 ± 44.6 vs 63.9 ± 43.5 mm2), a higher left ventricular ejection fraction (47.4 ± 21.0% vs 38.4 ± 20.6%) and higher maximum LAA flow velocities (26.3 ± 15.2 vs 19.3 ± 10.0 cm/s). Figures on the percentage of thrombus resolution in this study are comparable to those reported in the literature for the other OACs. We conclude that, in patients with AF, the use of edoxaban is associated with a >50% resolution of atrial thrombus at 4 weeks, similar to studies using VKAs and the other NOACs (ClinicalTrials.gov identifier number: NCT034899395).

Hypoplastic Left Atrial Appendage: A Case Report and Literature Review

BACKGROUND The left atrial appendage (LAA) has considerable variations in its size, shape, and spatial relationship with other cardiac structures. Absence of the LAA is a congenital cardiac condition usually identified by an imaging modality intended for other purposes. Absence of the LAA has been described in a total of 19 case reports so far; however, no cases of "hypoplastic" LAA in a real sense have ever been reported. CASE REPORT We herein report a case of hypoplastic, but not truly absent, LAA in a 76-year-old man scheduled for catheter ablation against atrial flutter. Preprocedural transesophageal echocardiography (TEE) performed in this patient to exclude intracardiac thrombosis failed to detect the LAA, although Doppler color-flow mapping revealed a jet signal spewed out into the main LA around where the LAA would be located. The LAA was also not detectable by routinely developed tomographic images from computed tomography (CT) angiography. Eventually, however, the multiplanar reconstruction into 3-dimensional volume rendering via the CT angiography identified a very small LAA. Those findings by TEE and CT led to a diagnosis of hypoplastic LAA. CONCLUSIONS Hypoplastic LAA should be kept in mind when considering LAA interventions as well as anticoagulation treatment. Multiple imaging modalities are necessary to recognize morphological aberration of the LAA.

Mechanical concordance between left atrium and left atrial appendage in nonvalvular atrial fibrillation: can it be exploited to avoid transesophageal echocardiography prior to electrical cardioversion during Covid-19 pandemic?

Transesophageal echocardiography (TEE) is the gold standard for assessing left atrial appendage (LAA) mechanic and thrombosis (LAAT); however, TEE is a high-risk procedure for viral transmission during coronavirus disease 2019 (COVID-19) pandemic. We investigated whether deformation indices of left atrium (LA) at transthoracic echocardiography (TTE) correlate with those of LAA assessed by TEE in nonvalvular atrial fibrillation (NVAF) patients undergoing electrical cardioversion (ECV). Consecutive patients with NVAF of ≥ 48 h or unknown duration, who underwent TEE and TTE at our Institution before ECV were retrospectively investigated. Standard echo-Doppler and LA and LAA myocardial strain and strain rate parameters were analyzed. A total of 115 NVAF patients (71.3 ± 8.1 yr/o, 59.1% men) were included: LAAT was diagnosed in 25 (21.7%) patients. Compared to patients without LAAT, those with LAAT had significantly higher CHA₂DS₂-VASc Risk score (4.5 ± 1.4 vs. 3.5 ± 1.1, p < 0.001), and lower ejection fraction (46.0 ± 14.8 vs. 57.6 ± 8.6%, p < 0.001). In LAAT patients, global strain of LA (8.7 ± 2.6 vs. 16.3 ± 4.5%, p < 0.001) and LAA (7.0 ± 1.7 vs. 11.7 ± 2.0%, p < 0.001) was significantly reduced compared to non-LAAT patients. A close relationship between left atrial strain reservoir (LASr) and LAA-global strain was demonstrated (r = 0.81). By univariable analysis, CHA₂DS₂-VASc Risk Score (OR 2.01, 95%CI 1.34–3.00), NT-proBNP (OR 1.36, 95%CI 1.19–1.54), ejection fraction (OR 0.92, 95%CI 0.88–0.96), E/e’ ratio (OR 2.07, 95%CI 1.51–2.85), and LASr (OR 0.39, 95%CI 0.25–0.62) were strongly associated with LAAT presence at TEE. By multivariable analysis, only LASr (OR 0.40, 95%CI 0.24–0.70) retained statistical significance. ROC curve analysis revealed that an LASr cut-off value ≤ 9.3% had 98.9% sensibility and 100% specificity to identify LAAT by TEE (AUC = 0.98). In patients with NVAF of ≥ 48 h or unknown duration, scheduled to undergo ECV, LA deformation assessment by TTE might substitute invasive measurement of LAA function by TEE, simplifying diagnostic approach and possibly contributing to reduce COVID-19 infection diffusion.

Coronary CTA to Investigate Predictive Value of Left Atrial Appendage for Cardiogenic Stroke in Patients with Nonvalvular Atrial Fibrillation

PURPOSE

To investigate the predictive value of changes in LAA size and function for cardiogenic stroke (CS) in patients with NVAF by coronary CTA examination. Materials and Method. 179 patients with NVAF were selected and grouped according to the outbreak of acute ischemic stroke and TIA within 2 years after coronary CTA examination. Those who met the criteria for CS were selected as cases (87 patients), and those neither stroke nor TIA as controls (92 patients). LAA size of selected patients was measured and data postprocessing was performed. The differences of baseline data and LAA parameters between groups were analyzed. The impacts of BMI, hyperlipidemia, the duration of AF, the LAAOA Index, and the LAAEF on CS were assessed by binary logistic regression. The predictive abilities of LAAOA Index, LAAEF, and the combined predictor were assessed by ROC curves.

RESULTS

Proportions of BMI ≥ 25, prevalence of hyperlipidemia, duration of AF, and LAAODmax, LAAODmin, LAAOA, LAAVmax, and LAAVmin with their correction index were greater in cases than controls. The LAAEF was lower in cases than that in controls. The binary logistic regression model showed an increase in LAAOA Index (P = 0.005) and a decrease in LAAEF (P < 0.001) were independent risk factors for CS. ROC curve analysis showed that the optimal cutoff values of LAAOA Index and LAAEF to predict CS were 3.16 cm²/m² and 38.71%, with AUC value of 0.712 and 0.734, respectively. The LAAOA Index-LAAEF combined predictor (AUC value = 0.786) was likely superior to either LAAOA Index or LAAEF.

CONCLUSIONS

Coronary CTA can provide additional valuable parameters, as a by-product of coronary artery assessment without additional radiation dose, for the risk assessment of CS in patients with NVAF. Coronary CTA may make up for the limitation of single indicator of CHA₂DS₂-VASc in guiding anticoagulation program, to reduce the incidence of embolism and bleeding events.

Left Atrial Appendage Ostial Stenosis: A Case Report and Literature Review

Patient: Female, 34-year-old

Final Diagnosis: Left atrial appendage ostial stenosis

Symptoms: No symptoms

Medication:—

Clinical Procedure: —

Specialty: Cardiology

Evaluating the novel parameters for assessing the LAA function and thrombus formation with nonvalvular atrial fibrillation

The dysfunction of left atrial appendage (LAA) is prone to form thrombus when atrial fibrillation (AF) sustained more than 48 h. Traditional 2D-TEE (transesophageal echocardiography) can not accurate evaluate the function of LAA. The purpose of this study is to analyze the relationship of LAA function parameters and thrombus formation in patients with non-valvular atrial fibrillation (NVAF) by real-time three-dimensional transesophageal echocardiography (RT-3D-TEE). High risk patients can be identified according to the characteristics of ultrasonic index in patients with left atrial appendage thrombosis, which has important clinical value and significance in the risk assessment, guiding treatment and judging prognosis. We examined the relationship between the echocardiographic parameters of LAA function and the incidence of thrombus in 102 NVAF patients. They underwent RT-3D-TEE and left atrial appendage thrombus (LAAT)/severe spontaneous echocardiographic contrast (SSEC) was found in 67 patients (thrombus group) but absent in the remaining 35 patients (non-thrombus group). After measured by QLAB software, the LAA functional parameters were significantly associated with LAAT/SEC formation. Univariate analysis indicated that AF time, LAD, LVEF, LAA-OAmax, LAAVmax, LAAVI and LAAEF demonstrated a positive association (P < 0.05). However, logistic regression analysis identified that AF time (OR:1.73, P < 0.05)、LAAEF (OR:4.09, P < 0.01)and LAAVI (OR:3.28, P < 0.01) were independent predictors of LAAT/SSEC. In patients with nonvalvular atrial fibrillation, echocardiographic parameters of LAA function are significantly associated with LAAT/SSEC.

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.

Interventional Left Atrial Appendage Closure Affects the Metabolism of Acylcarnitines

Background: Left atrial appendage closure (LAAC) represents the interventional alternative to oral anticoagulation for stroke prevention in atrial fibrillation (AF). The metabolism of acylcarnitines was shown to affect cardiovascular diseases. This study evaluates the influence of successful LAAC on the metabolism of acylcarnitines. Methods: Patients undergoing successful LAAC were enrolled prospectively. Peripheral blood samples for metabolomics measurements were collected immediately before (i.e., index) and six months after LAAC (i.e., mid-term). A targeted metabolomics analysis based on electrospray ionization–liquid chromatography–mass spectrometry (ESI–LC–MS/MS) and MS/MS measurements was performed. Results: 44 patients with non-valvular AF (median CHA₂DS₂-VASc score 4, median HAS-BLED score 4) and successful LAAC were included. Significant changes in acylcarnitine levels were found in the total cohort, which were mainly attributed to patients with impaired left ventricular and renal function, elevated amino-terminal pro-brain natriuretic peptide (NT-proBNP) and diabetes mellitus. Adjusted multivariable regression models revealed significant changes of five metabolites over mid-term follow-up: C2, C14:1, C16, and C18:1 decreased significantly (each p < 0.05); short-chain C5 acylcarnitine plasma levels increased significantly (p < 0.05). Conclusion: This study demonstrates that successful LAAC affects the metabolism of acylcarnitines at mid-term follow-up. Clinical Trial Registration: ClinicalTrials.gov Identifier: NCT02985463.

Highlights from the Ninth International Symposium of Thrombosis and Anticoagulation (ISTA IX), October 15, 2016, Salvador, Bahia, Brazil

To discuss and share knowledge about advances in the care of patients with thrombotic disorders, the Ninth International Symposium of Thrombosis and Anticoagulation was held in Salvador, Bahia, Brazil, on October 15, 2016. This scientific program was developed by clinicians for clinicians and was promoted by two major clinical research institutes-the Brazilian Clinical Research Institute and the Duke Clinical Research Institute of the Duke University School of Medicine. Comprising academic presentations and open discussion, the symposium had as its primary goal to educate, motivate, and inspire internists, cardiologists, hematologists, and other physicians by convening national and international visionaries, thought-leaders, and dedicated clinician-scientists. This paper summarizes the symposium proceedings.

Percutaneous Closure of Left Atrial Appendage affects Mid-Term Release of MR-proANP

The left atrial appendage (LAA) represents both a predisposing source of thrombus formation and of neuro-humoral haemostasis. This study aims to evaluate changes of biomarker expression before and after successful percutaneous closure of the LAA. Patients with atrial fibrillation and contraindication for oral anticoagulant therapy were enrolled. Blood samples were taken within 24 hours before (T1) and at least 6 months (mid-term) (T2) after successful implantation of LAA occlusion devices. Blood levels of high sensitivity troponin I and T (hsTnI, hsTnT), aminoterminal pro-brain natriuretic peptide (NT-proBNP) and mid-regional pro-atrial natriuretic peptide (MR-proANP) were evaluated at both time points. A total of 42 patients with successful percutaneous LAA closure were included. Median mid-term follow-up was of 183 days. HsTnT, hsTnI and NT-proBNP did not show any significant differences over time. Serum levels of MR-proANP increased significantly between immediate pre-intervention (T1: median = 245.7 pmol/l, IQR 155.8–361.3 pmol/l) and at mid-term follow-up (T2: median = 254 pmol/l, IQR 183.4–396.4 pmol/l) (p = 0.037). These results indicate, that percutaneous LAA closure affects neuro-humoral haemostasis by increasing MR-proANP serum levels at mid-term follow-up.

Intracardiac Hemostasis and Fibrinolysis Parameters in Patients with Atrial Fibrillation

AIMS

To identify intracardiac hemostasis or fibrinolysis abnormalities, which are associated with atrial fibrillation (AF) and increase the risk of thromboembolism.

PATIENTS AND METHODS

Patient group consisted of 24 patients with AF and control group included 14 individuals with other supraventricular tachycardia undergoing transcatheter radiofrequency ablation. Blood samples were drawn from the femoral vein (FV), left atrium (LA), and left atrial appendage (LAA) before the ablation procedure. Fibrinogen, factor VIII (FVIII) and factor XIII activity, von Willebrand factor (VWF) antigen, thrombin-antithrombin (TAT) complex, quantitative fibrin monomer (FM), plasminogen, α₂-plasmin inhibitor, plasmin-α₂-antiplasmin (PAP) complex, PAI-1 activity, and D-dimer were measured from all samples.

RESULTS

Levels of FVIII and VWF were significantly elevated in the FV and LA of AF patients as compared to controls. TAT complex, FM, PAP complex, and D-dimer levels were significantly elevated in the LA as compared to FV samples in case of both groups, indicating a temporary thrombotic risk associated with the catheterization procedure.

CONCLUSIONS

None of the investigated hemostasis or fibrinolysis parameters showed significant intracardiac alterations in AF patients as compared to non-AF controls. AF patients have elevated FVIII and VWF levels, most likely due to endothelial damage, presenting at both intracardiac and systemic level.

Percutaneous isolation of left atrial appendage thrombus

Most physicians regard left atrial appendage (LAA) thrombus as a contraindication for LAA occlusion due to risk of distal embolization which is a serious complication. Here we report a case of successfully implanted Amplazter cardiac plug without complication in elderly patients having LAA thrombus with recurrent embolic events despite oral anticoagulants for prevention of thromboembolic events. <Learning objective: LAA thrombus is not completely resolved in all cases and can be a potential source of stroke or embolization even during anti-coagulation. We would like to share a case that suffered from 6 strokes or embolizations despite anti-coagulation, warfarin or non-vitamin K antagonist oral anti-coagulants due to incomplete resolution of LAA thrombus. In this clinical situation, we can suggest LAA occlusion to isolate thrombus from LA and prevent further stroke or embolization.>.