Left Atrial Appendage Structure Research Articles

3D Transesophageal Echocardiography in the Selection of Occluder Size for Left Atrial Appendage Occlusion: A Meta-Analysis

Background: Left atrial appendage occlusion (LAAO) can effectively reduce the risk of stroke in atrial fibrillation (AF) patients. However, the structure of left atrial appendage (LAA) varies greatly among individuals, and the size of the occluder influences the surgical success rate and prognosis. This study used a meta-analysis to investigate whether three dimensional-transesophageal echocardiography (3D-TEE) can prompt physicians to select the appropriate size of the occluder, thereby improving prognosis in patients with LAAO. Methods: Studies on 3D-TEE-assisted selection of occluder sizes in the treatment of LAAO were searched in pubmed, cochrane, Web of Science, CNKI, Wanfang, and Weipu public databases from the inception of each database to June 10, 2024. The QUADAS-2 tool was used to assess the quality of the studies. Results: 10 studies published between 2016 and 2024 were finally included, with a total sample size of 552 cases. The maximum opening of the LAA obtained by 3D-TEE, coronary angiography (CAG) and video-assisted thoracic surgery (VATS) significantly correlated with the size of the occluder (p < 0.05). 3D-TEE was superior to 2D-TEE in measuring the maximum (p = 0.04) and minimum diameters (p = 0.01) of LAA openings, and to DSA in measuring depth (p = 0.01). Conclusion: 3D-TEE can be applied to obtain LAA opening data close to the size of the occluder with minimal side effects and to assist physicians in selecting the appropriate occluder.

Medical record data-enabled machine learning can enhance prediction of left atrial appendage thrombosis in nonvalvular atrial fibrillation

BackgroundAs a major complication of non-valvular atrial fibrillation (NVAF), left atrial appendage (LAA) thrombosis is associated with cerebral ischemic strokes, as well as high morbidity. Due to insufficient incorporation of risk factors, most current scoring methods are limited to the analysis of relationships between clinical characteristics and LAA thrombosis rather than detecting potential risk. Therefore, this study proposes a clinical data-driven machine learning method to predict LAA thrombosis of NVAF. MethodsPatients with NVAF from January 2014 to June 2022 were enrolled from Southwest Hospital. We selected 40 variables for analysis, including demographic data, medical history records, laboratory results, and the structure of LAA. Three machine learning algorithms were adopted to construct classifiers for the prediction of LAA thrombosis risk. The most important variables related to LAA thrombosis and their influences were recognized by SHapley Addictive exPlanations method. In addition, we compared our model with CHADS2 and CHADS2-VASc scoring methods. ResultsA total of 713 participants were recruited, including 127 patients with LAA thrombosis and 586 patients with no obvious thrombosis. The consensus models based on Random Forest and eXtreme Gradient Boosting LAA thrombosis prediction (RXTP) achieved the best accuracy of 0.865, significantly outperforming CHADS2 score and CHA2DS2-VASc score (0.757 and 0.754, respectively). The SHAP results showed that B-type natriuretic peptide, left atrial appendage width, C-reactive protein, Fibrinogen and estimated glomerular filtration rate are closely related to the risk of LAA thrombosis in nonvalvular atrial fibrillation. ConclusionsThe RXTP-NVAF model is the most effective model with the greatest ROC value and recall rate. The summarized risk factors obtained from SHAP enable the optimization of the treatment strategy, thereby preventing thromboembolism events and the occurrence of cardiogenic ischemic stroke.

Occlusion of Bilobulated Left Atrial Appendage Using the Dual-Watchman Technique: A Long-Term Follow-Up Study.

BackgroundPercutaneous left atrial appendage (LAA) occlusion has been considered an efficient alternative to oral anticoagulation to prevent embolic events in patients with non-valvular atrial fibrillation (NVAF). Due to the complexities and heterogeneous anatomy of the LAA structure, the single-device approach may not always fit a large bilobulated LAA. This study aimed to evaluate the feasibility and safety of one-stop dual Watchman implantation for patients with bilobulated LAA.MethodsIncluded in the analysis were patients who underwent complete LAA closure with dual Watchman devices between December 2015 and December 2021. The anatomic morphology, procedure characteristics, procedure safety, and procedural complications were analyzed. Cardiac CT or transesophageal ultrasound was obtained at 7 days, 6 months, 1 year, and 2 years post-operatively to evaluate the effect of occlusion.ResultsAmong the 330 patients who underwent LAA occlusion during the study period, 7 (2.1%) patients were occluded with one-stop implantation of the double Watchman strategy. Successful occlusion was achieved in all patients. One patient had the double-access sheath strategy for implantation, and 6 patients had only a single-access sheath strategy for implantation. Pericardial effusion occurred in one case during the 7-day perioperative period. There was no device embolization, thrombosis, or obvious peridevice leakage (≥l mm) during the 2-year follow-up, with the exception of two cases with 2 mm of incomplete LAA sealing.ConclusionThe one-stop implantation of a dual Watchman is feasible and safe and might provide a strategy to occlude a large bilobulated LAA when incomplete closure is inevitable with a single device.

Left atrial appendage structure predicts thromboembolic risk in 185 patients with crytogenic stroke/TIA without history of AF

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): Akerhus University Hospital Dept. of Cardiology Background Cryptogenic stroke/TIA (CS) is supposed to be associated with intracardiac thrombus formation and left atrial (LA) structure, in particular thrombus formation in left atrial appendage (LAA). However, there is little evidence if thromboembolic risk is associated with LAA morphology in patients with CS. Purpose We aimed to investigate, if different LAA morphology types may predict thromboembolic risk in patients with CS. Methods In this prospective study (mean follow-up 859 ± 226 days), 185 patients with CS (mean age 68 ±13 years, 33% female) without history of AF were included. All patients underwent complete transesophageal echocardiography in sinus rhythm after index CS (mean 5 ± 3days). Occurrence of LAA thrombus, sludge or spontaneous echo contrast (SEC) were defined as thromboembolic risk and LAA structure was evaluated by 2D and 3D transesophageal echocardiography. Multilobate LAA was defined as LAA with > 1 lobes. Results Of the 185 included patients, LAA type chicken wing was found in 79 (43%), type windsock in 64 (35%), type cactus in 35 (19%) and type cauliflower in 7 (4%). Thrombus formation occurred in 29/185 (16%), LAA sludge in 112/185 (61%), and LAA SEC in 74/185 (40%), which is increased compared to data in the general population. We found SEC in sludge in 65/112 (58%), SEC in thrombus in 18/29 (62%) and sludge in thrombus in 27/29 (93%). SEC and sludge were significantly associated with thrombus formation, (p < 0.001 and p < 0.01, respectively). Finally, thromboembolic risk occurred in 123 (67%) of all patients with CS. Moreover, LAA type chicken wing was significantly associated with thromboembolic risk (p < 0.01), while all other LAA types were not. Multilobate LAA occurred in 115 (62%) of all patients and predicted thromboembolic risk vs. non-lobated LAA (p= 0.04). In a multivariate analysis LAA type chicken wing and multilobate LAA were independently predictors of thromboembolic risk, figure 1. Conclusions Patients with cryptogenic stroke/TIA without history of AF showed increased thromboembolic risk, and SEC and sludge were significantly associated with LAA thrombus formation. Only LAA type chicken wing and multilobate LAA predicted independently thromboembolic risk in this study. Abstract Figure.

Trans-esophageal Echocardiographic Assessment of Left Atrial and Left Atrial Appendage Function in Atrial Fibrillation and Rheumatic Heart Disease.

Introduction: Rheumatic heart disease (RHD) is one of the most typical causes of atrial fibrillation in developing countries like India. The left atrial and left atrial appendage structure and function are deranged in atrial fibrillation and are a major source of thromboembolism. The goal of this study was to assess the left atrial and left atrial appendage function by transesophageal echocardiography in patients with atrial fibrillation and their comparison in patients with or without RHD.Methods: A total of 172 consecutive patients with atrial fibrillation with or without RHD were subjected to trans-esophageal echocardiography to assess and compare left atrial (LA) and left atrial appendage (LAA) function.Results: Out of 172 patients with atrial fibrillation, 100 were female (58.1%) and 72 were male (48.9%). The mean age was 54.11±12.3 years, and rheumatic heart disease (RHD) was the commonest cause of atrial fibrillation found in 121 (70.3%) patients. The mean left atrium diameter was significantly higher in RHD patients than in Non-RHD patients (52.08±10.13 vs. 46.67±6.78 mm, p=0.001). Mean left atrial ejection fraction was significantly lower in RHD patients as compared to Non-RHD patients (33.53±5.06 vs. 35.49±5.40%, p=0.024). The mean LAA orifice area of RHD patients was significantly higher than the Non-RHD patients (7.52±1.22 vs 6.94±1.17 mm2, p=0.005). Mean LAA emptying velocity was significantly lower in RHD patients than Non-RHD (20.49±3.95 vs. 22.8±5.96 ml/s, p=0.002).Conclusion: Rheumatic heart disease is still a common cause of atrial fibrillation in developing countries. LA and LAA function is impaired in atrial fibrillation, more in patients with rheumatic heart disease.

Feasibility and Accuracy of Automated Three-Dimensional Echocardiographic Analysis of Left Atrial Appendage for Transcatheter Closure

Procedural success of transcatheter left atrial appendage closure (LAAC) is dependent on correct device selection. Three-dimensional (3D) transesophageal echocardiography (TEE) is more accurate than the two-dimensional modality for evaluation of the complex anatomy of the left atrial appendage (LAA). However, 3D transesophageal echocardiographic analysis of the LAA is challenging and highly expertise dependent. The aim of this study was to evaluate the feasibility and accuracy of a novel software tool for automated 3D analysis of the LAA using 3D transesophageal echocardiographic data. Intraprocedural 3D transesophageal echocardiographic data from 158 patients who underwent LAAC were retrospectively analyzed using a novel automated LAA analysis software tool. On the basis of the 3D transesophageal echocardiographic data, the software semiautomatically segmented the 3D LAA structure, determined the device landing zone, and generated measurements of the landing zone dimensions and LAA length, allowing manual editing if necessary. The accuracy of LAA preimplantation anatomic measurement reproducibility and time for analysis of the automated software were compared against expert manual 3D analysis. The software feasibility to predict the optimal device size was directly compared with implanted models. Automated 3D analysis of the LAA on 3D TEE was feasible in all patients. There was excellent agreement between automated and manual measurements of landing zone maximal diameter (bias, -0.32; limits of agreement, -3.56 to 2.92), area-derived mean diameter (bias, -0.24; limits of agreement, -3.12 to 2.64), and LAA depth (bias, 0.02; limits of agreement, -3.14 to 3.18). Automated 3D analysis, with manual editing if necessary, accurately identified the implanted device size in 90.5% of patients, outperforming two-dimensional TEE (68.9%; P<.01). The automated software showed results competitive against the manual analysis of 3D TEE, with higher intra- and interobserver reproducibility, and allowed quicker analysis (101.9±9.3 vs 183.5±42.7sec, P<.001) compared with manual analysis. Automated LAA analysis on the basis of 3D TEE is feasible and allows accurate, reproducible, and rapid device sizing decision for LAAC.

Left atrial appendage morphology and the risk of stroke

Abstract In patients with non-valvular atrial fibrillation (AF) the risk of stroke is five times higher than in patients with sinus rhythm. Moreover, stroke is likely to be more severe in the AF patient population. Left atrial appendage (LAA) is the most common source of emboli in AF-related stroke. LAA thrombus is present in 15% of AF patients. Therefore, numerous studies aimed to evaluate the role of LAA structure and function in stroke formation. Higher LAA volume and bigger LAA orifice have been reported to be associated with increased risks of stroke. Moreover, not only the size, but also the shape of the LAA influences thrombus formation. The presence of an obvious bend in the proximal part of the dominant LAA lobe, described as chicken wing LAA morphology has been reported to be protective against stroke. However, other studies are not consistent with this finding and there is no consensus about LAA morphology categories. LAA has reservoir, contractile, electric and endocrine functions, that can provide essential information about the risk of clot formation and embolic events. Decreased LAA flow velocity, reflecting lower LAA contractility has been described to be associated with higher stroke risk. All in all, even if the LAA plays an important role in stroke formation, there are controversial literature data, therefore further studies are needed to evaluate the underlying mechanisms.

Association of Structure and Function of left atrial Appendage with Left atrial appendage Thrombus formation in patients with Rheumatic Heart Disease

Context: In patients with rheumatic heart disease (RHD), left atrial appendage (LAA) dilation and thrombus formation is widely known. LAA thrombus formation is a risk factor for stroke even in patients with sinus rhythm. The aim of this study was to determine an association between LAA structure and function with respect to thrombus formation and differences in LAA size and velocity between patients with sinus rhythm and those with atrial fibrillation (AF). Materials and Methods: We prospectively studied LAA structure and function in 120 patients with RHD by transthoracic echocardiography and/or transesophageal echocardiography by measuring left atrial (LA) dimension, LA area, LAAmax/min, LAA ejection fraction (EF), and LAA emptying velocity. Results: Four out of 48 patients with sinus rhythm had LAA thrombus. In 72 patients with AF, 32 had LAA thrombus. Patients with LAA thrombus had lower mean LAA EF and emptying velocity both variables P-value is same (P&lt;0.0001 and P&lt;0.0001) Patients with LAA thrombus had increased mean LAA max and LAA min as compared to LAA max and LAA min in patients without LAA thrombus (P 0.008 for mean LAA max and P&lt;0.0001 for LAA min respectively). Patients with AF with LAA thrombus had greater LAAmax compared to that in patients with AF without LAA thrombus (P &lt; 0.0001). Doppler demonstrated a recognizable sawtooth LAA outflow velocity pattern in 32 of 36 (88.9%) patients with LAA thrombus versus 32 of 84 (38.1%) patients without LAA thrombus. Conclusions: We conclude that LAA contractility is reduced in RHD with LAA thrombus, and loss of both contractility and LAA dilation is associated with increased risk of thrombus formation and hence the risk of stroke.

Application of Echocardiographic Three-Dimensional Printed Left Atrial Appendage Model to Guide Transcatheter Left Atrial Appendage Occlusion

This study aimed to determine the feasibility of three dimensional (3D) printed left atrial appendage (LAA) models based on 3D transesophageal echocardiography (3D TEE) data and its application value in the interventional LAA closure. Eighteen patients who had interventional LAA occlusion underwent pre-procedure TEE and cardiac CT. TEE 3D full volume raw data of the LAA were acquired and post-processed to create a 3D model file. Two modes of the LAA model (cardiac chamber model, cardiac wall model) were printed out by 3D printer. The LAA morphologic classification was assessed by 3D printed chamber model and the LAA dimension measurement was performed on 3D printed wall model. Additionally, preoperative rehearsal was performed on the 3D printed cardiac wall models in the cases with complex LAA structure. In all the patients, 3D TEE full volume data of the LAA were successfully reprocessed and printed out as 3D LAA chamber models and 3D LAA wall models. The consistency of LAA morphologic classification judgment based on 3D printed models and cardiac CT was 0.918 (P<0.01).The LAA ostium dimension measured on 3D printed model was greater than 2D TEE (P<0.01) and smaller than X-ray (P=0.02), and the LAA depth was greater than 2D TEE (P<0.01) whereas was not significantly different with X-ray (P=0.54).Based on 3D model morphology, there were 3 complex LAA which were recommended a particular occlusion plan after pre-procedure rehearsal on 3D model. The occlusion success rate was 100%. Echocardiographic 3D printing technique is feasible and have promising value in supporting planning the transcatheter LAA occlusion.

Assessment of the left atrial appendage structure and morphology: comparison of real-time three-dimensional transesophageal echocardiography and computed tomography

In this study, the left atrial appendage (LAA) structure and morphology were assessed using real-time three-dimensional transesophageal echocardiography (RT3D-TEE) and enhanced cardiac computed tomography (CT) scanning, and the two measurements obtained using these different techniques were compared. Two hundred nonvalvular atrial fibrillation (NVAF) patients who were prepared to undergo radiofrequency ablation were enrolled, and 62 controls were enrolled prospectively. RT3D-TEE and CT were performed, and the following parameters were measured: LAA orifice diameter, area, depth, maximum volume, and emptying velocity. The differences between the NVAF patients and controls were compared, and the differences and correlations in the LAA parameters between the two imaging techniques were assessed. The NVAF patients had significantly bigger orifice sizes, orifice areas, and maximum volumes, and lower emptying rates. The AF cohort had roughly equal proportions of the four morphological types, whereas the controls predominantly had the windsock type. A Bland-Altman analysis demonstrated that the LAA measurements obtained using RT3D-TEE were lower than those obtained with the CT. However, linear regression analysis showed the good correlations between the RT3D-TEE and CT measurements of the LAA orifice area, depth and volume (r = 0.86, 0.63, and 0.75, respectively). The use of RT3D-TEE for the visualization and quantitative analysis of LAA parameters is feasible, and the obtained measurements correlate well with those obtained with cardiac CT. This technique may be an ideal tool for guiding LAA occlusion procedures, and combining these two methods may enhance the accuracy of LAA measurements.

The Value of 3D Printing Models of Left Atrial Appendage Using Real-Time 3D Transesophageal Echocardiographic Data in Left Atrial Appendage Occlusion: Applications toward an Era of Truly Personalized Medicine

Aims and Objectives: The objective of this study was to assess the clinical feasibility of generating 3D printing models of left atrial appendage (LAA) using real-time 3D transesophageal echocardiogram (TEE) data for preoperative reference of LAA occlusion. Background: Percutaneous LAA occlusion can effectively prevent patients with atrial fibrillation from stroke. However, the anatomical structure of LAA is so complicated that adequate information of its structure is essential for successful LAA occlusion. Emerging 3D printing technology has the demonstrated potential to structure more accurately than conventional imaging modalities by creating tangible patient-specific models. Typically, 3D printing data sets are acquired from CT and MRI, which may involve intravenous contrast, sedation, and ionizing radiation. It has been reported that 3D models of LAA were successfully created by the data acquired from CT. However, 3D printing of the LAA using real-time 3D TEE data has not yet been explored. Methods: Acquisition of 3D transesophageal echocardiographic data from 8 patients with atrial fibrillation was performed using the Philips EPIQ7 ultrasound system. Raw echocardiographic image data were opened in Philips QLAB and converted to ‘Cartesian DICOM' format and imported into Mimics® software to create 3D models of LAA, which were printed using a rubber-like material. The printed 3D models were then used for preoperative reference and procedural simulation in LAA occlusion. Results: We successfully printed LAAs of 8 patients. Each LAA costs approximately CNY 800-1,000 and the total process takes 16-17 h. Seven of the 8 Watchman devices predicted by preprocedural 2D TEE images were of the same sizes as those placed in the real operation. Interestingly, 3D printing models were highly reflective of the shape and size of LAAs, and all device sizes predicted by the 3D printing model were fully consistent with those placed in the real operation. Also, the 3D printed model could predict operating difficulty and the presence of a peridevice leak. Conclusions: 3D printing of the LAA using real-time 3D transesophageal echocardiographic data has a perfect and rapid application in LAA occlusion to assist with physician planning and decision making.

The left atrial appendage: from embryology to prevention of thromboembolism.

The left atrial appendage (LAA) is the main source of thromboembolism in patients with non-valvular atrial fibrillation (AF). As such, the LAA can be the target of specific occluding device therapies. Optimal management of patients with AF includes a comprehensive knowledge of the many aspects related to LAA structure and thrombosis. Here we provide baseline notions on the anatomy and function of the LAA, and then focus on current imaging tools for the identification of anatomical varieties. We also describe pathogenetic mechanisms of LAA thrombosis in AF patients, and examine the available evidence on treatment strategies for LAA thrombosis, including the use of non-vitamin K antagonist oral anticoagulants and interventional approaches.

GW26-e0742 Assessment of the left atrial appendage structure and function of the non-valvular atrial fibrillation by real-time three-dimensional transesophageal echocardiography

GW26-e0742 Assessment of the left atrial appendage structure and function of the non-valvular atrial fibrillation by real-time three-dimensional transesophageal echocardiography

Murine left atrium and left atrial appendage structure and function: echocardiographic and morphologic evaluation.

Aim of this study was to provide an echocardiographic protocol for the description of the normal murine venous reservoir (atrium, appendage and pulmonary veins) and to investigate the possibility to use this approach to discriminate changes on left atrium (LA) and left atrial appendage (LAA) in a stress-induced model such us myocardial infarction. Global left ventricular function and the venous reservoir were assessed by a Vevo2100 in 20 female C57BL/6N. LA and LAA were also studied in 10 CD-1 and 10 FVB mice, whereas modifications investigated in 15 C57BL/6N subjected to coronary artery ligation. Left ventricle function was evaluated as well as pulsed Doppler mitral valve, pulmonary vein, and LAA velocities. From 2D view monoplane LA volumes were obtained and LAA long axis measured. Macroscopic inspection with casts and immunohistochemistry were performed. Results show that compared to humans, in C57BL/6N mice left atrium was disproportionately smaller (5.2±1.4μL) than the left ventricle (53±8μL) and connected through a duct by a large LAA and posteriorly to three pulmonary veins. The LA volume increased 2-fold during reservoir with two distinct phases, early and late divided by a short pause. LAA long axis (4.1±0.5mm) was almost 2 times longer than the LA. LAA flow volume together with LA volume reservoir account for about 36% of stroke volume and the rest was provided by conduit flow. Linear regressions showed that stroke volume was strongly influenced by LAA flow, LA early filling volume and left ventricle base descent. Moreover, we also report the ability to assess LA and LAA in other mice strains and discriminate size increase following myocardial infarction. In conclusion, we performed a complete characterization of murine left venous reservoir establishing an optimized protocol that can be used in both investigative and pharmacological studies requiring rapid and serial determination of cardiac structure and function.

Application of Mimics three-dimensional imaging in percutaneous left atrial appendage closure with Watchman system

The three-dimensional (3D) structure of left atrial appendage (LAA) in atrial fibrillation patients were reconstructed by Mimics 3D imaging system, aiming at guiding for selection of both the size and location of the closure devices and making preliminary risk assessment of LAA closure with Watchman system. Inclusion criteria were: ten voluntary patients with both atrial fibrillation and indication for LAA closure aging from 40 to 85 years old with contraindication for oral anticoagulants or unwillingness to take long-term oral anticoagulation therapy from May to December 2014. 3D reconstruction of LAA was preoperatively made by Mimics 3D imaging system. With the Mimics 3D reconstruction model and the results of both transesophageal echocardiography (TEE) and LAA radiography, the size and location for the closure device were chosen. The devices were planted at the ostium of the LAA. Ten atrial fibrillation patients were enrolled (average age: (66.3±11.9) years old) and all successfully implanted with the Watchman LAA closure devices. Nine of them were with non-valvular atrial fibrillation with average CHADS2-VAS score (3.2±1.7) and HAS-BLED score (2.7±1.6). The rest one was a valvular atrial fibrillation patient with the history of the percutaneous balloon mitral valvuloplasty (PBMV) without surgical indications of mitral valve replacement (MVR). There was no blood leakage around the device by regular postoperative TEE and LAA radiography examinations. There were no complications of bleeding, embolism, or stroke through both at peri-operative period and at 1 month follow-up post procedure. Preoperative Mimics 3D reconstruction of LAA by Mimics 3D imaging system among atrial fibrillation patients provides essential information guiding the successful LAA closures.

Complex Left Atrial Appendage Morphology and Left Atrial Appendage Thrombus Formation in Patients With Atrial Fibrillation

In patients with atrial fibrillation (AF), most thrombus forms in the left atrial appendage (LAA). However, the relation of LAA morphology with LAA thrombus is unknown. We prospectively enrolled 633 consecutive patients who were candidates for catheter ablation for symptomatic drug-resistant AF. Transesophageal echocardiography (TEE) was performed to assess LAA thrombus. LAA structure was assessed by 3-dimensional TEE. LAA orifice area, depth, volume, and number of lobes were measured on reconstructed 3-dimensional images. Clinical characteristics and echocardiographic measures were compared to determine variables predicting LAA thrombus. Excluded were 69 (10.9%) patients who met the exclusion criteria. Finally, this study comprised 564 patients, of whom LAA thrombus was observed in 36 (6.4%) patients. Multivariate analysis revealed CHADS2 (Congestive heart failure, Hypertension Age>75, Diabetes mellitus and prior Stroke or transient ischemic attack) score (P=0.002), left ventricular ejection fraction (P=0.01), degree of spontaneous echo contrast (P=0.02), left atrial volume (P=0.02), and number of LAA lobes (P<0.001) to be independently associated with thrombus formation. Most patients with LAA thrombus (32/34, 94.4%) had ≥3 LAA lobes, whereas LAA thrombus was observed in only 2 (0.7%) of 296 patients with 1 or 2 lobes. LAA volume significantly decreased in patients maintaining sinus rhythm after catheter ablation (P=0.0009). Number of LAA lobes did not change in any patient. Complex LAA morphology characterized by an increased number of LAA lobes was associated with the presence of LAA thrombus independently of clinical risk and blood stasis. This study suggests that LAA morphology might be a congenital risk factor for LAA thrombus formation in patients with AF.

Intracardiac Echocardiography for Detection of Thrombus in the Left Atrial Appendage

Background— Transesophageal echocardiography (TEE) is the gold standard for the exclusion of thrombi in the left atrial appendage (LAA) before ablation for atrial fibrillation. Intracardiac echocardiography (ICE) is used to assist atrial fibrillation ablation; however, it can also be used for LAA imaging. The aim of our study was to determine whether ICE could replace TEE and to identify the optimal ICE placement for LAA visualization. Methods and Results— Seventy-six consecutive patients (56 men; mean age, 55±9.6 years) scheduled for atrial fibrillation ablation underwent TEE before the procedure and LAA assessment by ICE. An 8F AcuNav probe was introduced into right atrium, pulmonary artery, and coronary sinus. LAA structure was analyzed by the echocardiographer and electrophysiologist who were blinded to the results of TEE. ICE probe was positioned in the right atrium in all patients, in the pulmonary artery in 64 of 74 (86%) patients, and in the coronary sinus in 49 of 74 (66%) patients. The LAA was properly visualized in 56 of 64 (87.5%) patients from the pulmonary artery versus 13 of 49 (26%) patients from the coronary sinus ( P &lt;0.001). From the right atrium, the whole LAA cavity could not be seen in any patient. In those patients in whom LAA was visualized properly by ICE, a perfect agreement between ICE and TEE was obtained (both techniques detected LAA thrombus in 2 patients and excluded LAA thrombus in the remaining patients). Conclusions— ICE can be used safely and effectively for the evaluation of LAA in patients undergoing atrial fibrillation ablation. ICE imaging from pulmonary artery is accurate for LAA visualization. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01371279.

Abstract 17795: Left Atrial Appendage Volume Reflects Severity of Mitral Regargitation: A Three-Dimensional Transesophageal Echocardiography Study

Background: Left atrial (LA) size is well known to reflect volume overload condition such as mitral regurgitation (MR). However, the effects to left atrial appendage (LAA) have not been well defined. LAA structure has multilobed complicated three-dimensional structures. Recent development of real-time 3-dimensional transesophageal echocardiography (RT3D-TEE) has enabled us to examine morphology and determine absolute volumes of LAA without geometrical assumptions. We investigated the relationship between MR severity and LAA volume. Methods: Seventy-four patients with MR who underwent RT3D-TEE were studied. All measurements were performed off-line software. Maximal LAA orifice area, depth and volume, and the number of LAA lobes were assessed (Figure). We also measured LAA emptying flow velocity (LAAev) as the average of 3 consecutive cardiac cycles in patients in normal sinus rhythm and 5 consecutive cardiac cycles in patients with atrial fibrillation. MR grade was evaluated by vena contracta width (VCW). In 58 patients, we also determined the maximal LA volume by the Simpson method from apical views by 2-dimensional transthoracic echocardiography. Pulsed Doppler E, tissue Doppler E' and E/E' were also measured. Results: Mean LAA orifice area was 5.0±3.8 cm 2 , LAA volume was 11±10 ml, LA volume was 116±57ml, and LAAev was 41±23 cm/sec. Patients with moderate to severe MR had larger LAA orifice area, LAA volume, and LA volume than patients with mild MR (Table). In contrast, there were no relationship between MR severity, the number of LAA lobes and LAAev. 3D derived LAA volume was correlated with VCW significantly (r=0.51, p&lt;0.01). Conclusion: LAA volume was associated with MR severity.

Measurement of left atrial appendage size by transesophageal echocardiography.

Transesophageal echocardiography (TEE) is the most common imaging method for evaluating left atrial morphology. Recent advances in 64-slice multidetector computed tomography (64-MDCT) allow accurate measurement of left atrial appendage (LAA) volume. The aim of this study was to evaluate the accuracy of LAA sizing by TEE in comparison with 64-MDCT in patients with atrial fibrillation. Electrocardiogram-gated 64-MDCT and TEE were performed within 2days in 18 consecutive patients (63±9years old, 12 males, 5 paroxysmal atrial fibrillation) with nonvalvular atrial fibrillation. LAA area and LAA volume were measured at end-systole by TEE and 64-MDCT, respectively. The largest LAA area was measured on TEE image. Five patients were in sinus rhythm during examinations. In all patients, LAA was clearly visualized; the largest area of LAA was 9.3±3.9mm(2) and the LAA volume was 21.6±7.5ml. A significant correlation between LAA area and LAA volume was observed (p=0.0003, r=0.75). TEE allows a detailed evaluation of the LAA structure by two-dimensional imaging. LAA size could be evaluated by TEE despite its morphological complexity, i.e., sac-like or multilobed structure.

Stroke Prevention in Atrial Fibrillation: Atrial Appendage Closure

The left atrial appendage (LAA) is the primary nonvalvular cause of cardioembolic stroke in patients with atrial fibrillation (AF). Warfarin and direct thrombin inhibitors such as dabigatran are presumed to prevent formation of LAA thrombus, and are first-line treatments to prevent ischemic stroke in AF. However, these medications carry many contraindications such as hemorrhage, and can interact with many drugs and supplements. Epicardial and endovascular techniques for occlusion of LAA are being explored, whether to mitigate the need for anticoagulation in patients at risk of bleeding or as a first-line therapy to reduce the risk of thromboembolic stroke. The purposes of this article are to 1) review the LAA structure and its potential contribution to ischemic stroke; 2) discuss the results of surgical and endovascular trials of LAA occlusion on risk of stroke and adverse events in AF patients; and 3) present early data on devices in development.