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To investigate whether we can rule out the left atrial appendage (LAA) thrombus in patients with atrial fibrillation (AF) using different scanning protocol by Cardiovascular Computed Tomography (CCT). We retrospectively reviewed the CCT images of 138 patients with AF to assess LAA thrombus. Patients with no thrombosis diagnosed by preoperative CCT should be confirmed using intraoperative findings as the reference standard. Patients diagnosed with thrombosis were then compared with TEE examination. Different CT scanning protocol were used to assess LAA thrombus according to individual differences. In 126 cases, there was no thrombus in the LAA evaluated by preoperative CCT, and it was confirmed in the subsequent radiofrequency operation. CCT has the accuracy of 100% in confirming the absence of thrombus in the LAA. Twelve thrombi were detected by CCT, eleven thrombi were detected by TEE. Only one patient had different results between CCT and TEE. We could use different CT scanning protocol to rule out LAA thrombus according to individual differences. In some special patients, LAA thrombus can be evaluated by CCT instead of TEE.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice and is known to be associated with significant morbidity and mortality. Previous studies suggested a link between inflammation and AF by findings of increased inflammatory markers in AF patients. However, it has not been finally clarified whether inflammation is a systemic or a local phenomenon reflecting an active inflammatory process in the heart. To address this subject, human left atrial appendage tissues were obtained from 10 patients who underwent cardiac surgery and subjected to immunohistochemical analysis. The number of inflammatory CD3-positive T cells significantly increased from patients with sinus rhythm to paroxysmal AF and persistent AF, respectively. Interestingly, in patients with persistent AF, these cells were frequently arranged in small clusters. Subsequently, the number of inflammatory CD3-positive T cells decreased and was significantly lower in patients with permanent AF than in patients with persistent AF. Inflammatory CD20-positive B cells could only be detected very occasionally in all AF subgroups and were not locatable in patients with SR. Hence, our data emphasize the potential prominent role of the cellular component of the immune system in the development and perpetuation of AF.

ObjectivesTo evaluate the association between left atrial appendage volume (LAAV) and atrial fibrillation (AF) recurrence after catheter ablation (CA) and explore the potential mechanism.DesignSystematic review and meta-analysis.Data sourcesPubMed, EMBASE, Web of Science and Cochrane Library databases were searched systematically from inception through 28 September 2024 to identify relevant studies.Eligibility criteriaObservational studies that estimated the association between LAAV and AF recurrence.Data extraction and synthesisTwo independent investigators screened studies for inclusion and extracted data. Statistical heterogeneity was assessed using the Cochrane Q-test and I², with p<0.1 or I² > 50% indicating significant heterogeneity. This study used a random-effects model to account for potential heterogeneity. The quality of the included studies was assessed using the Newcastle–Ottawa Scale (NOS), Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I tool) and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. Publication bias was examined through funnel plots and Egger’s test.ResultSeventeen studies (3078 patients) were included. Meta-analysis of 11 studies suggested that LAAV was significantly associated with the risk of AF recurrence in both univariate (HR 1.06, 95%CI 1.04 to 1.08, p<0.01; I2=49.7%) and multivariate analyses (HR 1.10, 95%CI 1.05 to 1.16, p<0.01; I2=77.4%). The relationship between LAAV and recurrence of persistent AF (HR 1.11, 95% CI 1.03 to 1.20, p<0.05; I² = 73.0%) was significant. However, no significant association was found for paroxysmal AF (HR 1.01, 95% CI 0.94 to 1.07, p>0.05; I² = 0%). Meta-analysis of 13 studies suggested that patients with recurrence had larger LAAV values than those without recurrence (standardised mean difference (SMD) 0.54, 95% CI 0.36 to 0.71, p<0.01; I2=67.9%), and persistent AF patients had larger LAAV values than paroxysmal AF (SMD 0.29, 95% CI 0.02 to 0.57, p=0.05; I2=60.6%). Sensitivity analyses did not change these results. Subgroup analyses largely aligned with the overall findings, though study design and sample size contributed to heterogeneity. The mean NOS scores indicated moderate to high study quality; ROBINS-I assessments showed that most studies had a low to moderate overall risk of bias; and the GRADE approach rated the certainty of outcome evidence as low.ConclusionsOur study suggests that LAAV may be a significant predictor of AF recurrence after CA. Incorporating LAAV into pre-ablation screening may enhance risk stratification, guiding tailored follow-up and treatment strategies.PROSPERO registration numberCRD42022339910.

Telocytes are interstitial cells with long, thin processes by which they contact each other and form a network in the interstitium. Myocardial remodeling of adult patients with different forms of atrial fibrillation (AF) occurs with an increase in fibrosis, age-related isolated atrial amyloidosis (IAA), cardiomyocyte hypertrophy and myolysis. This study aimed to determine the ultrastructural and immunohistochemical features of cardiac telocytes in patients with AF and AF + IAA. IAA associated with accumulation of atrial natriuretic factor was detected in 4.3–25% biopsies of left (LAA) and 21.7–41.7% of right (RAA) atrial appendage myocardium. Telocytes were identified at ultrastructural level more often in AF + IAA, than in AF group and correlated with AF duration and mitral valve regurgitation. Telocytes had ultrastructural signs of synthetic, proliferative, and phagocytic activity. Telocytes corresponded to CD117 + , vimentin + , CD34 + , CD44 + , CD68 + , CD16 + , S100 - , CD105 - immunophenotype. No significant differences in telocytes morphology and immunophenotype were found in patients with various forms of AF. CD68-positive cells were detected more often in AF + IAA than AF group. We assume that in aged AF + IAA patients remodeling of atrial myocardium provoked transformation of telocytes into “transitional forms” combining the morphological and immunohistochemical features with signs of fibroblast-, histiocyte- and endotheliocyte-like cells.

The relationship between atrial fibrillation (AF), blood flow disturbances and thrombus formation is well-established in humans. Thrombi primarily form in the left atrial appendage (LAA), but the specific role of LAA morphology remains unclear. Felines, despite rarely experiencing AF, present a valuable model for studying human heart diseases. Cats exhibit a high incidence of cardiomyopathies, often accompanied by significant left atrial dilation and thrombus formation. This unique aspect prompts research focusing on LAA morphology and function in relation to thrombus development. Our study, using advanced image processing and fluid simulations on 24 cat hearts ranging from normal to cardiomyopathy subjects, aims to find distinctions in left atrium (LA) and LAA morphologies, blood flow patterns and their relation to thrombus formation. Significantly different variables in feline heart groups included: heart weight, LAA volume, LA volume, ostium area, ostium area-to-heart weight ratio, centreline length and velocity at the LAA ostium. Fluid simulations revealed lower LAA blood flow velocities and increased thrombotic risk in cases with thrombi. Our study enhances the understanding of LAA structure and function, offering insights into thrombus formation mechanisms with potential implications for better managing thrombosis risk in patients.

Atrial fibrillation (AF) is the most common clinically relevant cardiac arrhythmia. AF poses patients at increased risk of thromboembolism, in particular ischemic stroke. The CHADS2 and CHA2DS2-VASc scores are useful in the assessment of thromboembolic risk in nonvalvular AF and are utilized in decision-making about treatment with oral anticoagulation (OAC). However, OAC is underutilized due to poor patient compliance and contraindications, especially major bleedings. The Virchow triad synthesizes the pathogenesis of thrombogenesis in AF: endocardial dysfunction, abnormal blood stasis, and altered hemostasis. This is especially prominent in the left atrial appendage (LAA), where the low flow reaches its minimum. The LAA is the remnant of the embryonic left atrium, with a complex and variable morphology predisposing to stasis, especially during AF. In patients with nonvalvular AF, 90% of thrombi are located in the LAA. So, left atrial appendage occlusion could be an interesting and effective procedure in thromboembolism prevention in AF. After exclusion of LAA as an embolic source, the remaining risk of thromboembolism does not longer justify the use of oral anticoagulants. Various surgical and catheter-based methods have been developed to exclude the LAA. This paper reviews the physiological and pathophysiological role of the LAA and catheter-based methods of LAA exclusion.

Background Left atrial appendage aneurysm is a rare cardiac mass, with only a few cases reported. There are usually no specific symptoms, and a few patients visit the doctor with symptoms. Case presentation A 20-year-old male presented to our hospital with a “pericardial cyst found by medical evaluation in another hospital for 2 years.” Cardiac ultrasound performed at clinics of our hospital suggested a cystic dark area in the left ventricular lateral wall and the anterior lateral wall, consistent with a pericardial cyst and mild mitral regurgitation. After further relevant examinations and ruling out contraindications, an excision of the left atrial appendage aneurysm was performed under general anesthesia and cardiopulmonary bypass with beating—heart. The postoperative pathological results identified that: (left atrial appendage) fibrocystic wall-like tissue with a focal lining of the flat epithelium, consistent with a benign cyst. Conclusion Left atrial appendage aneurysms are rare and insidious. They are usually found by chance during medical evaluations. If the location is not good or the volume is too large, then compression symptoms or arrhythmia, thrombosis and other concomitant symptoms will occur. Surgical resection is presently the only effective radical cure for a left atrial appendage aneurysm.

The left atrial appendage (LAA) is the typical origin for intracardiac thrombus formation. Whether LAA morphology is associated with increased stroke/TIA risk is controversial and, if it does, which morphological type most predisposes to thrombus formation. We assessed LAA morphology in stroke patients with cryptogenic or suspected cardiogenic etiology and in age- and gender-matched healthy controls. LAA morphology and volume were analyzed by cardiac computed tomography in 111 patients (74 males; mean age 60 ± 11 years) with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology other than known atrial fibrillation (AF). A subgroup of 40 patients was compared to an age- and gender-matched control group of 40 healthy individuals (21 males in each; mean age 54 ± 9 years). LAA was classified into four morphology types (Cactus, ChickenWing, WindSock, CauliFlower) modified with a quantitative qualifier. The proportions of LAA morphology types in the main stroke group, matched stroke subgroup, and control group were as follows: Cactus (9.0%, 5.0%, 20.0%), ChickenWing (23.4%, 37.5%, 10.0%), WindSock (47.7%, 35.0%, 67.5%), and CauliFlower (19.8%, 22.5%, 2.5%). The distribution of morphology types differed significantly (P<0.001) between the matched stroke subgroup and control group. The proportion of single-lobed LAA was significantly higher (P<0.001) in the matched stroke subgroup (55%) than the control group (6%). LAA volumes were significantly larger (P<0.001) in both stroke study groups compared to controls patients. To conclude, LAA morphology differed significantly between stroke patients and controls, and single-lobed LAAs were overrepresented and LAA volume was larger in patients with acute ischemic stroke of cryptogenic or suspected cardiogenic etiology.

Background:Occlusion of the left atrial appendage (LAA) is thought to reduce the risk of thromboembolic events in patients with atrial fibrillation.Objective:To examine the LAA and its relationship to neighbouring structures that may be put at risk when intervening to occlude its os.Methods:31 heart specimens were examined grossly. Four of the LAAs were processed for histological examination and endocasts were made from 11 appendages. The diameters of the LAA os and proximity to the left superior pulmonary vein, mitral valve and left anterior descending artery were measured and areas of thin atrial wall in the vicinity were noted.Results:The LAA orifice was oval shaped in all cases with a mean (SD) diameter of 17.4 (4) mm (range 10–24.1). The mean (SD) distances of the LAA orifice to the left superior pulmonary vein and mitral valve were 11.1 (4.1) mm and 10.7 (2.4) mm, respectively. The left anterior descending, circumflex artery and, in 6 cases, the sinus node artery, were in close proximity to the LAA. Pits or troughs and areas of thin atrial wall were found in 57.7% of hearts within a 20.9 mm radius from the os. Histology showed small crevices and areas of very thin wall within the trabeculated appendage.Conclusions:The LAA orifice is oval shaped and thin areas of appendage wall and atrial wall are common. Potentially, the left superior pulmonary vein, mitral valve and anterior descending coronary artery can be at risk during occlusion of the os.

Histomorphologic parameters of atrial appendages removed during the Cox-Maze procedure have been shown to correlate with recurrence of atrial fibrillation. While amyloid deposition has been noted within atrial appendages, the incidence and significance remains incompletely understood. More accurate amyloid typing methodologies and targeted pharmacotherapeutics have recently been developed, prompting pathologists to provide more detailed information about the type of amyloid identified in such samples. This study sought to fully characterize the morphologic characteristics of atrial amyloid as well as its incidence and clinical significance. Tissue archives were queried for atrial appendages removed during the cardiac surgeries (2010–2014). Patient demographics, imaging features, and salient clinical findings were recorded. Pattern and extent of amyloid deposition were recorded. Typing of the amyloid protein, when present, was performed on a subset of cases by laser capture microdissection with mass spectrometry-based proteomic analysis. A total of 383 atrial appendages from 345 consecutive patients were included in the study (mean age, 69 years; range, 26–92 years). Amyloid was present in 46% of patients. A linear relationship was observed between age and presence of atrial amyloidosis. Women were more likely to have atrial amyloidosis. Two distinct morphologies of amyloid were observed: filamentous and nonfilamentous, and correlated perfectly with amyloid type (filamentous = AANF-type amyloid; nonfilamentous = ATTR-type amyloid). Filamentous deposits were observed in 91% of those with amyloid. Amyloid was more likely to be found in the left atrial appendage than the right. Patients with atrial amyloid, irrespective of type, were more likely to have experienced stroke or TIA and more likely to have atrial arrhythmia preoperatively. Postoperatively, those with atrial amyloid are more likely to experience recurrence of arrhythmia than those who did not have atrial amyloid. Understanding the morphologic characteristics of AANF-type amyloid will allow for identification by the light microscopy and obviates the need for expensive ancillary typing techniques. The finding of nonfilamentous amyloid, should still prompt confirmation of amyloid type so that targeted therapy may be employed.