Assessment Of Left Atrial Appendage Research Articles

Left atrial appendage emptying velocity and left ventricular function as predictors of inotropic support in patients undergoing elective off-pump coronary artery bypass grafting

Abstract Background: Patients undergoing elective off-pump coronary artery bypass grafting (CABG) are at risk of hemodynamic instability, ischemia, arrhythmia, and dysfunction. These events need to be managed by pharmacological supports or relieving of mechanical obstruction (octopus) of the heart to maintain the hemodynamic stability. There is a paucity of data on the effect of left ventricular (LV) dysfunction on left atrial appendage (LAA) emptying velocity. We evaluated the relationship between LV function and LAA emptying velocity and requirement of inotropic support perioperatively. Materials and Methods: In this prospective open-label all-comer study, fifty patients undergoing elective off-pump CABG under general anesthesia, we measured LAA emptying velocity by pulsed wave Doppler and evaluated if it could predict the need for inotropes perioperatively. It is a case series of 50 patients without a comparator arm. We measured pulsed wave Doppler across the mitral valve leaflet and early mitral inflow velocity (Evel) and late mitral inflow velocity, tissue Doppler at the lateral annulus of the mitral valve (e’) and also calculated the ratio of Evel and e’. Need for inotrope in the intraoperative and postoperative period was captured perioperatively. Vasoactive-inotropic score (VIS) was calculated for all the patients. Results: The VIS was significant (P < 0.0001, with odds ratio of 131.6 and confidence interval of 95% (0.9–1). However, there was no significant correlation between ejection fraction (EF) and VIS (P = 0.87). In patients with the need of inotropes, LAA emptying velocity was significantly increased in the postgrafting period as compared to the pregrafting period (75.64 cm/s vs. 57.9 cm/s, P < 0.001). Conclusion: The assessment of LAA emptying velocity value was a useful predictor of the need of inotropic support during off-pump surgery, especially during Obtuse marginal and Ramus grafting. This study paves the need of larger case–control studies to validate the findings.

Invasively diagnosed HFpEF in AF associated with functional remodelling of the left atrial appendage: implications for stroke risk

Abstract Background HFpEF commonly coexists with atrial fibrillation (AF). The influence of coexisting HFpEF on function of the left atrial appendage (LAA) and risk of stroke remains unknown. Objective To use invasive hemodynamic assessment and multi-modality imaging to evaluate the influence of underlying HFpEF on LAA function in patients with symptomatic AF. Methods Patients with AF and preserved ejection fraction undergoing AF ablation were prospectively recruited. All participants underwent invasive diagnosis of HFpEF using established hemodynamic criteria. Participants were classified as ‘HFpEF’ when mean left atrial pressure (mLAP) was >15mmHg and ‘early HFpEF’ when mLAP rose to above 15mmHG after infusion of 500mls saline. For LAA assessment, participants underwent 1) contrast-enhanced cardiac CT to evaluate LAA volume, 2) transesophageal echocardiography to investigate emptying velocities (LAAEV), filling velocities (LAAFV) and LAA ejection fraction (LAAEF) and 3) high-density electroanatomic mapping to assess LAA bipolar voltages. Results Of 115 participants recruited, 55 had ‘HFpEF’, whilst 29 had ‘early HFpEF’ and 31 had ‘no HFpEF’. Table 1 demonstrates the baseline characteristics and LAA structural and functional parameters across the three groups. The HFpEF group was characterized by higher BMI (p=0.008) and higher prevalence of hypertension (p=0.023) but there was no significant difference in age (p=0.194) or gender (p=0.376). LAA volume was not significantly different across the three groups (p=0.509). However, the HFpEF group demonstrated reduced LAAEV (p=0.021) and LAAFV (p=0.015) compared to early HFpEF and no HFpEF. HFpEF was also associated with reduced LAAEF (p=0.015) and reduced LAA bipolar voltages in sinus rhythm (p=0.028) compared to no HFpEF. In a multivariable analysis HFpEF group was the only independent predictor of reduced LAAEV (p=0.015). Conclusions Invasively diagnosed HFpEF in AF is common and associated with significantly reduced LAA function. The coexistence of HFpEF may therefore be a determinant of future stroke risk in patients with AF.

A quantitative gain‐independent assessment of the left atrial appendage as a method of thromboembolic risk stratification

Visual assessment of the left atrial appendage (LAA) by echocardiography for the presence of thrombus is inherently qualitative. However, whether quantitative assessments can provide increased value over qualitative assessment has not been thoroughly examined. One hundred and thirty-eight patients (mean age 59 ± 13 years, 70% male) undergoing transesophageal echocardiography prior to pulmonary vein isolation or electrical cardioversion were retrospectively studied. LAA were examined by two expert readers and identified as thrombus, sludge, spontaneous echocardiograph contrast, or normal. LAA were then separately examined to calculate a gain-independent ratio between the average pixel density of the LAA cavity and that of the LAA wall (C/W ratio). C/W ratio was significantly related with qualitative LAA analysis (p < 0.0001) and with thromboembolic events (OR 1.60, 95% CI 1.095-2.347, p=0.02). The C/W ratio (AUC 0.73, 95% CI 0.60-0.86) was a reliable predictor for future thromboembolic events when compared to expert reader LAA assessment (Expert Reader 1 AUC=0.72, 95% CI 0.53-0.90; Expert Reader 2 AUC=0.69). The C/W ratio may be a complementary method to adjudicate thromboembolic risk in patients with AF that is readily quantifiable at time of TEE.

Abstract 12043: Computed Tomography Angiography Assessment of Left Atrial Appendage Post Occluder Device

Introduction: Device related thrombosis (DRT) is an indication for continuation of anticoagulation for patients undergoing left atrial appendage (LAA) occlusion. There is a paucity of data in regards to the definition of DRT on coronary CT angiography (CTA) in patients with WATCHMAN FLX TM (Boston scientific) device implantation. Methods: This is a single center experience of using CTA for follow up in patients post WATCHMAN FLX TM implantation. 37 consecutive patients who underwent WATCHMAN FLX TM implantation at our center and had CTA performed at first follow up were included. CTA images were analyzed for the presence of hypo-attenuated thickening (HAT) on the device, device positioning, peridevice gap, angulation, compression percentage, depth of implant from coumadin ridge and enhancement in the LAA compared to left atrium (LA). Results: Among 37 patients with CTA follow up, HAT was noted in 28 patients (75%). 38% of these patients had HAT &gt;3 mm. LAA patency (LAA/LA ratio of &gt;25%) was seen in 7 patients (10%), 4 with gaps around the device and the rest secondary to trans-fabric leak. Gap around the device was noted in 13 patients (35%). 6 of these 13 patients had &gt;4 mm gap; 5/6 patients had HAT and 3/6 patients had &gt;25% enhancement in the LAA compared to LA. Increased compression % on both CTA and intraprocedural TEE was associated with absence of HAT (p=0.0003) as well as better sealing on CTA (LAA/LA ratio of &gt;25%) (p=0.04). 6 months follow up is available on only 18 patients; only one of these patients had stoke and that patient did not have HAT on the CT scan. Conclusions: Definition of thrombus on WATCHMAN FLX TM device is not clearly defined on CTA. HAT on CTA could be artifact from the device knob and gutter or visible endothelialization around the device. Further studies with multimodality imaging and clinical correlation are needed to help determine normal cut offs for HAT on these CTAs.

Value of Left Atrial Appendage Function Measured by Transesophageal Echocardiography for Prediction of Atrial Fibrillation Recurrence after Radiofrequency Catheter Ablation.

Atrial fibrillation (AF) recurrence after radiofrequency catheter ablation (RFCA) remains a challenging issue. This study aims to explore the left atrial appendage function by transesophageal echocardiography (TEE) and assess its value in predicting AF recurrence following RFCA in paroxysmal AF patients. Eighty-one patients with paroxysmal AF that underwent RFCA were recruited. TEE was performed before ablation with the assessment of left atrial appendage emptying flow velocity (LAAeV). AF recurrence occurred in 24 patients (29.6%) within 12 months after RFCA. The left atrium diameter (LAD) and left atrium volume index (LAVI) were both significantly higher in the recurrence group compared to the non-recurrence group, while the LAAeV was significantly lower in the recurrence group. LAD, LAVi and LAAeV were univariately significant risk factors for AF recurrence after ablation. Based on receiver operating curve (ROC), LAAeV < 40.5 cm/s, LAVi > 40.5 mL and LAD > 41 mm were identified as cut-off values for predicting AF recurrence. In multivariate regression analysis LAAeV < 40.5 cm/s (HR 8.194, 95% CI 2.980–22.530, p < 0.001) was identified as the only statistically significant independent predictor of AF recurrence, as the statistical significance threshold was not achieved for LAVI > 40.5 mL and LAD > 41 mm (p = 0.319; p = 0.507, respectively). A low LAAeV was the only important independent predictor of AF recurrence within 1 year after first RFCA.

Abstract 13949: Quantitative Assessment of the Left Atrial Appendage as a More Reliable Method of Thromboembolic Risk Stratification

Introduction: Assessment of the left atrial appendage (LAA) in patients with atrial fibrillation (AF) undergoing cardioversion for thromboembolic risk stratification is inherently qualitative. Oftentimes, interobserver assessment may disagree, leading to differences in risk stratification and patient management. We propose a novel method of quantitative LAA assessment and examine its predictive value for future thromboembolic events. Hypothesis: Evaluation of LAA using ImageJ pixel density quantification software in patients with AF will be superior to qualitative assessment by expert readers in assessing and predicting future thromboembolic risk. Methods: A total of 124 patients (mean age 59 ± 13 years, 70% male) undergoing transesophageal echocardiography to exclude LAA thrombus prior to radiofrequency pulmonary vein isolation or electrical cardioversion for AF were retrospectively studied. LAA were examined by two expert readers and identified as thrombus ( n = 9), sludge ( n = 11), spontaneous echocontrast ( n = 90), or normal ( n = 138). LAA were then separately examined using ImageJ to calculate a gain-independent ratio between the average pixel density of the LAA cavity and the average pixel density of the LAA wall (C/W ratio). Results: There was significant disagreement between the two expert readers in LAA assessment (weighted Kappa 0.510, p &lt; 0.0001). Qualitative LAA analysis was significantly related with C/W ratio ( p &lt; 0.0001) and thromboembolic events ( p &lt; 0.0002). C/W ratio was also significantly related with thromboembolic events (OR 1.60, 95% CI 1.095 - 2.347, p &lt; 0.0152). According to Area Under the Curve (AUC) of the ROC curve, C/W ratio (AUC 0.73, 95% CI 0.60 - 0.86) was a more reliable predictor for future thromboembolic when compared to qualitative LAA assessment (AUC 0.72, 95% CI 0.53-0.90). Conclusions: Quantitative LAA assessment using the C/W ratio provided by ImageJ software is more reliable than qualitative assessment by expert readers for identifying future thromboembolic events while reducing reader variability.

Left atrial appendage occlusion with the Amplatzer Amulet: update on device sizing.

The present paper analyzes the role of different imaging modalities for left atrial appendage (LAA) assessment and the recommended specific measurements to improve device selection with regard to the Amulet device. Morphological LAA assessment is one of the pivotal factors to achieve proper LAA sealing and potentially reduce the risk of complications by minimizing manipulation inside the appendage. Eight experienced physicians in LAAO were asked to contribute in the preparation of a device sizing consensus manuscript after comprehensive assessment of previous published data on LAA imaging/measurement. LAA morphology is often complex and requires more detailed spatial resolution and 3-dimensional assessments to reduce the risk of mis-sizing. Traditionally, upsizing of devices based upon the largest measured LAA diameters have been used. However, this may lead to oversizing in markedly elliptical appendages. Thus, when 3D imaging modalities are available, utilizing the LAA mean diameters might be a better alternative. Operators should also note the systematic biases in differences in measurements obtained with different imaging modalities, with CT giving the largest measurements, followed by 3D-TEE, and then 2D-TEE and angiography. In fact, for 2D imaging techniques (2D-TEE and angiography), LAA diameters tend to be underestimated, and therefore, LAA largest diameters seem to be still the best option for device sizing. Some specific anatomies such as proximal chicken-wing or conic LAAs may require different measurements and implantations to achieve implant success. In conclusion, LAA mean diameters might be a better alternative to largest diameters when 3D imaging modalities are available.

Simultaneous Functional and Morphological Assessment of Left Atrial Appendage by 3D Virtual Models.

Purpose The left atrial appendage (LAA) is responsible for thrombus formation in patients with atrial fibrillation. The evaluation of both LAA function and morphology is crucial for the patient characterization and the preprocedural planning of LAA closure intervention. Despite the availability of 3D imaging modalities, the current standard image analysis is based on manual delineation of the LAA contours on 2D views. Methods In this study, a comprehensive approach based on a full 3D analysis of the tomographic dataset by surface extraction and processing (3D-S) is presented. The proposed method allows extracting functional and morphologic information in the entire cardiac cycle by minimalizing manual user interaction. The proposed methodology has been validated on ten computer tomography datasets. Results The proposed 3D-S method was feasible in all cases. Reproducibility was improved with respect to the reference 2D manual procedure (2D-S) (coefficient of variation 2.9 vs. 4.1% for diastolic ostium area; 3.8 vs. 6.1% for systolic ostium area; 2.4 vs. 5.3% for diastolic LAA volume; 2.7 vs. 5.9% for systolic LAA volume; and 7.7 vs. 17.1% for LAA ejection fraction). No significant differences were found between 2D-S and 3D-S measurements. Conclusions In this study, we introduced a fully 3D approach for LAA characterization, allowing the simultaneous assessment of LAA function and geometry. The proposed approach could be used to improve the patient selection and the best sizing of the device for LAA closure and to allow a patient-specific 3D printing.

IMPROVED DETECTION OF LEFT ATRIAL APPENDAGE THROMBUS UTILIZING MICROBUBBLE CONTRAST

Transesophageal echocardiography (TEE) is the primary tool for the assessment of left atrial appendage (LAA) thrombus. However, diagnostic accuracy remains sub-optimal with reports of cerebral embolic events approaching 1% after TEE-cardioversion. Microbubble contrast is anecdotally useful in

Accuracy of Commonly-Used Imaging Modalities in Assessing Left Atrial Appendage for Interventional Closure: Review Article.

Periprocedural imaging assessment for percutaneous Left Atrial Appendage (LAA) transcatheter occlusion can be obtained by utilizing different imaging modalities including fluoroscopy, magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound imaging. Given the complex and variable morphology of the left atrial appendage, it is crucial to obtain the most accurate LAA dimensions to prevent intra-procedural device changes, recapture maneuvers, and prolonged procedure time. We therefore sought to examine the accuracy of the most commonly utilized imaging modalities in LAA occlusion. Institutional Review Board (IRB) approval was waived as we only reviewed published data. By utilizing PUBMED which is an integrated online website to list the published literature based on its relevance, we retrieved thirty-two articles on the accuracy of most commonly used imaging modalities for pre-procedural assessment of the left atrial appendage morphology, namely, two-dimensional transesophageal echocardiography, three-dimensional transesophageal echocardiography, computed tomography, and three-dimensional printing. There is strong evidence that real-time three-dimensional transesophageal echocardiography is more accurate than two-dimensional transesophageal echocardiography. Three-dimensional computed tomography has recently emerged as an imaging modality and it showed exceptional accuracy when merged with three-dimensional printing technology. However, real time three-dimensional transesophageal echocardiography may be considered the preferred imaging modality as it can provide accurate measurements without requiring radiation exposure or contrast administration. We will present the most common imaging modality used for LAA assessment and will provide an algorithmic approach including preprocedural, periprocedural, intraprocedural, and postprocedural.

Assessment of left atrial appendage by echocardiography and its implications in clinical practice

Assessment of left atrial appendage by echocardiography and its implications in clinical practice

Morphologic Assessment of the Left Atrial Appendage in Patients with Atrial Fibrillation by Gray Values–Inverted Volume-Rendered Imaging of Three-Dimensional Transesophageal Echocardiography: A Comparative Study with Computed Tomography

Accurate assessment of left atrial appendage (LAA) morphology is crucial in determining an LAA occlusion strategy. The aim of this study was to develop a novel echocardiographic volume-rendered imaging technique to visualize LAA morphology. This was a retrospective study. Forty patients with atrial fibrillation who underwent three-dimensional (3D) transesophageal echocardiography (TEE) and cardiac computed tomographic angiography (CCTA) before catheter ablation were enrolled. Full-volume 3D data were acquired and displayed in gray values-inverted (GVI) mode. Threshold segmentation and interactive segmentation were used to create 3D digital replicas of the LAA chambers. The morphologic classification, number of lobes, and dimensions of the LAA were analyzed and compared with the data obtained with CCTA. LAA morphology and measurements were successfully acquired via CCTA and 3D GVI TEE in all 40cases. In terms of LAA morphologic classifications, 19 cases of chicken wing, eight of windsock, nine of cauliflower, and four of cactus morphology were determined using 3D GVI TEE, and 20 cases of chicken wing, eight of windsock, eight of cauliflower, and four of cactus morphology were determined using CCTA. The κ value between these two methods was 0.963. Measurements of maximal diameter, minimal diameter, and area of the ostia and the depth of the LAAs were larger when based on the 3D GVI transesophageal echocardiographic data than when using cardiac computed tomographic angiographic data (P<.01); however, there was agreement between the results. Formed thrombi were well displayed by both computed tomography and 3DGVI TEE. Three-dimensional GVI TEE can be used to acquire LAA morphologic volume-rendered images that are similar to computed tomographic volume-rendered images, and it shows promise as a feasible and valuable modality for planning individual LAA occlusion procedures.

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.

Assessment of Left Atrial Appendage Function by 2-Dimensional Speckle-Tracking Imaging in Transesophageal Echocardiography

PP-196 The aim of this study was to investigate whether strain and strain rate (StR) values measured by 2-dimensional speckle tracking echocardiography are useful for the assessment of left atrial appendage (LAA) function. Transesophageal echocardiography was performed in consecutive patients with

Assessment of left atrial appendage function by transthoracic echocardiography in non-valvular atrial fibrillation

Background: Transesophageal echocardiography (TEE) is currently accepted for assessment of left atrial appendage (LAA) function in patients (pts) with non-valvular atrial fibrillation (AF). Yet, TEE might not be used for screening and follow-up purposes. Purpose: To evaluate spectral tissue Doppler imaging (TDI) parameter obtained by transthoracic echocardiography (TTE) to assess LAA function in pts with non-valvular AF. Methods: The study included 91 pts with non-valvular AF (mean age 61±10 ys; 60 men (65,9%) and 31 women (34,1%); 67 (73,6%) had concomitant hypertension, 27 (29,7%) - coronary artery disease, 65 (71,4%) – heart failure, 9 pts (9,9%) – history of stroke or transient ischemic attack). LAA apex movement velocity was measured by TTE TDI (Avel) and LAA ejection velocity (Evel) – by TEE. According to the value of Evel pts were divided into two groups: group 1 (G1) - Evel ≥30,0 cm/s, n = 63, and group 2 (G2) - Evel <30,0 cm/s, n = 28. The groups were comparable by gender and concomitant diseases. Data are expressed as median with range and 95% confidence intervals (CI). Results: It was found, that Avel was significantly lower in G2 than in G1 (6,0 (5,0-7,5) and 9,4 (8,1-11,1) cm/s, accordingly, p<0,001) and significantly related to Evel (Spearman's r= 0,57, p<0,001). Area under ROC-curve for Avel for discrimination G1 and G2 was 0,866 (0,788-0,944) with cut-off value 7,8 cm/s. The discrimination ability of Avel at this cut-off was as follows: sensitivity 81,8% (95% CI 59,7-94,8), specificity 80,7% (95% CI 68,1-90,0), positive predictive value 62,1% (95% CI 42,3-79,3) and negative predictive value 92,0% (95% CI 80,8-97,8). Conclusion: Avel measured by TTE might be used an alternative to Evel measured by TEE for assessment of LAA function in pts with AF.

Role of Cardiac Imaging for Catheter-based Left Atrial Appendage Closure.

Thromboembolic stroke is the most serious complication in patients suffering from Atrial Fibrillation. Atrial thrombi have a predilection to form in the left atrial appendage. Accordingly, oral anticoagulation is recommended for patients with high risk of stroke. However, it is widely underused and problems of compliance are associated with serious risk of bleeding or inefficacy. In these patients with non-valvular atrial fibrillation, percutaneous occlusion of the left atrial appendage might help to reduce the risk of thromboembolism. Cardiac imaging plays a crucial role at all stages of this procedure and trans-esophageal echocardiography represents the current gold-standard for the assessment of the left atrial appendage. Cardiac imaging is mandatory to precisely determine the left atrial appendage anatomy and to select the appropriate size for the device. Finally, real time three-dimension echocardiography is a powerful additional tool that improves the safety profile of the procedure. 3D-transoesophageal echocardiography allows for the accurate assessment of left atrial appendage anatomy and helps determine if it's suitable for device implantation. Finally, it also allows for continuous visualization of all intracardiac devices and catheters during the procedure, and the clear delineation of device positioning in the left atrial appendage.

Real time 3-dimensional transesophageal echocardiography is more specific than 2-dimensional TEE in the assessment of left atrial appendage thrombosis

In patients indicated for detection of intraatrial thrombus (T), 2-dimensional transesophageal echocardiography (2DTEE) is routinely used but differentiation between T and trabeculae or artifacts in the left atrial appendage (LAA) is often difficult. To compare the diagnostic value of real time 3D-transesophageal echocardiography (RT3DTEE) and 2DTEE in the assessment of LAA thrombosis. One hundred and ten consecutive patients (73M, aged 64+-13) were examined by 2DTEE. In terms of possible T, individual pts were diagnosed as negative (N2), uncertain trabecular finding (U2), other/artifacts (O2), and clearly positive (T2). The RT3DTEE was then applied and the categorization repeated (N3,U3,O3 and T3, resp.). Finally, the operator decided whether the RT3DTEE. A: had an additional diagnostic value, and/or B: changed the definite diagnosis of thrombosis. N2:71; U2:17; O2:19;T2:3; N3:97; U3:1; O3:12; T3:0. Ad A/ RT3DTEE enabled us to refine or change the diagnosis in 26/110 cases. 17 pts were switched from group U2 to N3, 7:O2-N3 and 2:T2-N3. 12 pts from O2 and 1 pt from T2 remained unclarified. Ad B/ Diagnoses were changed in 6 patients after RT3DTEE. A very suspicious T2 was found in 3 patients. In 1, the finding was requalified definitely as musculi pectinati. In the second patient, the finding was re-categorized as just a spontaneous echocontrast without T. In another 4 patients, T in LAA was definitely excluded after RT3DTEE (1 patient switched from U2 to N3, 3 from O2 to N3). In another 13, the findings remained unclear, mostly because of poor quality image. No real thrombus was found in this study. RT3DTEE provides additional information, which may be helpful in the differentiation of thrombus from other findings. It is particularly useful in the identification of muscular trabeculae in the left atrial appendage.

Is It Time to Move on from Two‐Dimensional Transesophageal to Three‐Dimensional Transthoracic Echocardiography for Assessment of Left Atrial Appendage? Review of Existing Literature

Left atrial appendage (LAA) has unique anatomical and physiological properties, which make it a common site for thrombus formation in many cardiovascular and systemic diseases. Assessment of LAA for thrombus thus becomes important in many clinical situations and two-dimensional transesophageal echocardiography (2D TEE), which allows excellent quality images of LAA because of its close proximity to esophagus is routinely used for this purpose. However, it is a semiinvasive procedure, requires more time and involves some degree of patient discomfort. With some training and experience, two-dimensional transthoracic echocardiography (2D TTE) can visualize LAA in most patients with good acoustic windows. A disadvantage of both 2D TTE and 2D TEE is that they provide only a thin slice or section of cardiac structures at any given time limiting their utility in comprehensively assessing the LAA for thrombus. On the other hand, live/real time three-dimensional (3D) TTE overcomes this limitation of both 2D TTE and 2D TEE because of its ability to encompass whole of the LAA in three-dimensions in the acquired data set, which can then be cropped and sectioned systematically at any desired angulation to more definitively look for clot. 3D TTE is also useful in differentiating a clot from pectinate muscles in the LAA, which can mimic a thrombus resulting in patient mismanagement. In addition, 3D TTE is helpful in sectioning a clot for lysis, which has implications in clot resolution. We reviewed the existing literature comparing the relative advantages and disadvantages of 3D TTE versus 2D TEE and found that in patients with good acoustic windows 3D TTE had similar efficacy for detecting LAA thrombus.

Transesophageal Echocardiographic Short-Axis Views of the Left Atrial Appendage

Left atrial appendage (LAA) thrombus has a known association with embolic events, but diagnosis with echocardiography has proved to be an ongoing challenge. The correct diagnosis is important for decisions on surgical or percutaneous closure and anticoagulation. Although 3-dimensional transesophageal echocardiography has been shown to be more geometrically accurate for LAA assessment than 2-dimensional transesophageal echocardiography,1-3 should the diagnosis be suspected intraoperatively and no 3-dimensional machine is available, multiple 2-dimensional orthogonal views of LAA lesions should improve the diagnostic yield.

Left Atrial Appendage Dimensions Predict the Risk of Stroke/TIA in Patients With Atrial Fibrillation

Risk of Stroke/TIA in Patients With Atrial Fibrillation. Most strokes in patients with atrial fibrillation (AF) arise from thrombus formation in left atrial appendage (LAA). Our aim was to identify LAA features associated with a higher stroke risk in patients with AF using magnetic resonance imaging and angiography (MRI/MRA). The study included 144 patients with nonvalvular AF who were not receiving warfarin and who underwent MRI/MRA prior to catheter ablation for AF. LAA volume, LAA depth, short and long axes of LAA neck, and numbers of lobes were measured. Of the 144 patients, 18 had a prior stroke or transient ischemic attack (TIA) (13 and 5, respectively). Compared with patients who had no history of stroke/TIA, these patients were older, had higher prevalence of hypertension and hyperlipidemia and had higher LAA volume (22.9 ± 9.6 cm(3) vs. 14.5 ± 7.1 cm(3) , P < 0.001). Their LAA depth (3.76 ± 0.9 cm vs. 3.21 ± 0.8 cm, P = 0.006) and the long and short axes of the LAA neck (3.12 ± 0.7 cm vs. 2.08 ± 0.7 cm, P < 0.001; 2.06 ± 0.5 cm vs. 1.37 ± 0.4 cm, P < 0.001, respectively) were larger. Using stepwise logistic regression model, the only statistically significant multivariable predictors of events were age (OR = 1.21 per year, 95% CI 1.06-1.38, P = 0.004), aspirin use (OR = 0.039, 95% CI 0.005-0.28, P = 0.001), and LAA neck dimensions (short axis × long axis) (OR = 3.59 per cm(2) , 95% CI 1.93-6.69, P < 0.001). LAA dimensions predict strokes/TIAs in patients with AF. LAA assessment by MRI/MRA can potentially be used as an adjunctive tool for risk stratification for embolic events in AF patients.