Prediction of embolism in atrial fibrillation: classification of left atrial thrombi by transesophageal echocardiography

The current study was undertaken to clarify the relationship between cerebral/arterial embolism and the morphology of left atrial thrombi. Forty-one patients with atrial fibrillation and left atrial thrombi were followed for 1 year, using transesophageal echocardiography (TEE) to study how the shape, site, movability, number and maximum dimension of left atrial thrombi are related to embolism. Left atrial thrombi were classified by their shape and movability into movable ball (MB) type (n=13), fixed ball (FB) type (n=17) and mountain (MN) type (n=11). The thrombi were also classified by location into the interior section (n=3), middle section (n=8), and the entrance section (n=19) of the left atrial appendage, and the section outside of the left atrial appendage (n=11). The rate of embolism in the MB-type group was significantly higher than that in the other groups (ie, MB 76.9% vs FB 17.6% (p<0.01) vs MN 9.1%; p<0.01), which indicates that the MB-type thrombus is an important risk factor for cerebral/arterial embolism.     

Left atrial thrombi in non-rheumatic atrial fibrillation: assessment of prevalence by transesophageal echocardiography

To determine the prevalence of left atrial thrombus in hospitalized patients with non-rheumatic atrial fibrillation, 48 patients were consecutively studied with single-plane transesophageal echocardiography. There were 23 males (48%) and 25 females (52%). The mean age was 66±11 years (range 43–87). Thrombus was detected in 13 patients (27%) 11 were confined to the left atrial appendage, 1 to the atrial body and appendage, and 1 to the left upper pulmonary vein. Prevalence of atrial thrombus was not different among those patients with or without previous stroke [4/16 (25%) vs 9/32 (28%), p=NS] or between patients > 65 years and patients 65 years old (p=NS). Atrial thrombus was detected more frequently in patients with reduced left ventricular global systolic function than in those with normal function [7/14 (50%) vs 6/34 (17%), p<0.05]. In patients with spontaneous contrast echoes in the left atrium, thrombi were visualized more often than in those without spontaneous echoes [10/24 (41%) vs 3/24 (12%), p<0.05]. The finding of the atrial spontaneous contrast echoes was more frequent among patients with reduced left ventricular global systolic function [11/14 (78%) vs 13/34 (37%), p<0.02].We conclude that in hospitalized patients with non-rheumatic atrial fibrillation the prevalence of left atrial thrombus is high. Reduced left ventricular global systolic function identifies a subset of patients at high risk for formation of thrombus in the left atrium.     

The role of transesophageal echocardiography in the detection of left atrial thrombi

Sensitivity of transthoracic echocardiography in the detection of left atrial thrombi, in particular thrombi confined to the left atrial appendage, is surprisingly low (33%-72%). Concerning the detection of left atrial thrombi, transthoracic echocardiography appears as an inadequate technique in patients with suspected cardiogenic embolism with a success rate of only 0.8% in earlier, and about 3% in recent studies. Imaging from the esophagus substantially increases the detection rate for left atrial thrombi, and is the only clinically relevant semiinvasive technique to diagnose thrombi confined to the left atrial appendage. Transesophageal echocardiography has markedly increased the diagnostic power of cardiovascular ultrasound in patients with suspected cardiogenic embolism and/or atrial fibrillation. Meta-analysis of pooled studies using the transesophageal approach in these patients revealed thrombi within the left atrial cavity in about 7% and within the atrial appendage in about 12% of cases.     

Analysis of the left atrial appendage by magnetic resonance angiography in patients with atrial fibrillation

BACKGROUND: Recent interest has focused on the left atrial appendage (LAA) in the setting of atrial fibrillation as a potential source of thromboembolism and stroke, which may be amenable to permanent occlusion by a variety of investigational catheter-delivered devices. Precise anatomic characterization of the LAA is necessary to determine the suitability of a patient for device placement and for device selection and sizing. OBJECTIVES: The purpose of this study was to perform detailed three-dimensional characterization of LAA size and geometry by magnetic resonance angiography. METHODS: Fifty patients with chronic atrial fibrillation undergoing cardiac magnetic resonance angiography in preparation for catheter ablation of atrial fibrillation were analyzed for LAA volume, neck size, depth, and overall geometry. RESULTS: The average LAA volume was 17.3 +/- 6.7 mL, with a depth of 26.6 +/- 4.9 mm and a "neck" diameter of 20.0 +/- 5.3 mm x 14.1 +/- 4.7 mm. The average number of LAA lobes was 1.4 +/- 0.7 (range 1-4). Substantial interpatient variability was present in the relative dimensions and morphology of the LAA. There was a significant correlation between left atrial size and LAA neck dimensions. CONCLUSION: There is significant heterogeneity in LAA size and dimensions among patients with atrial fibrillation. Device occlusion of the LAA may require devices that are available in multiple sizes/shapes or that can adapt to this heterogeneity.     

Usefulness of transesophageal echocardiography for the detection of left atrial thrombi in patients with rheumatic heart disease

Transesophageal (TEE) and transthoracic (TTE) echocardiograms were performed in 110 patients with rheumatic heart disease to evaluate the usefulness of these methods for the detection of left atrial thrombi. TEE was better than TTE for detecting left atrial thrombi (21 vs 9). The thrombi not detected by TTE were in the left atrial appendage in ten and over the left atrial posterior wall in two. Patients with left atrial thrombi had significantly smaller mitral valve area (P less than 0.01) and greater left atrial dimension (P less than 0.05) than those without. All patients with left atrial thrombi had atrial fibrillation. Thirty-one patients underwent surgical intervention and 13 were found to have left atrial thrombi. TEE detected left atrial thrombi in all 13 patients with a sensitivity of 100%, specificity of 100%, and accuracy of 100%, while TTE detected left atrial thrombi in only nine of these 13 patients with a sensitivity of 69.2%, specificity of 100%, and accuracy of 87.1%. Thus, TEE is superior to TTE for the detection of left atrial thrombi, especially for those thrombi located in the left atrial appendage and along the left atrial posterior wall.     

Comparison of ability to identify left atrial thrombus by three-dimensional tomography versus transesophageal echocardiography in patients with atrial fibrillation

We sought to determine the potential use of recently introduced cardiac 3-dimensional computed tomography as an alternative to transesophageal echocardiography for examination of the left atrial appendage. Our data suggest that computed tomography is a potential alternative for assessing the anatomy of the left atrial appendage and for detecting thrombi.     

Relation of left atrial size to function as determined by transesophageal echocardiography

One hundred thirty-nine patients who underwent transesophageal echocardiographic studies were grouped by their maximal left atrial (LA) volumes, and their stroke volumes, emptying fractions, and fractional shortening were calculated. In large atria, an inverse relation was found between further increases in LA volume and LA function, determined by emptying fractions and fractional shortening.     

Intrapericardial left atrial aneurysm diagnosed by transoesophageal echocardiography and nuclear magnetic resonance imaging

A case of intrapericardial left atrial aneurysm is described in a 38-year-old woman, who presented with invalidating paroxysmal atrial fibrillation. The diagnosis was suspected by 2D-echocardiography, and confirmed by transoesophageal echocardiography and magnetic resonance imaging. Chest X-ray, right and left ventricular and coronary angiography were normal. The aneurysm was surgically removed, and the patient has subsequently remained free from symptoms.     

MRI imaging of a left atrial mass misinterpreted by transesophageal echocardiography

Magnetic resonance imaging of the heart was used in a patient with a history of recurrent episodes of transient ischemic attacks in whom a left atrial mass was suspected on transesophageal echocardiography. The use of MRI clarified a diagnosis of a diaphragmatic hernia.     

Prevalence of left atrial thrombi and spontaneous echo contrast in dilative cardiomyopathy evaluated by transesophageal echocardiography

Abstracts

Prevalence of left atrial thrombi and spontaneous echo contrast in dilative cardiomyopathy evaluated by transesophageal echocardiography     

Diagnosis of left atrial appendage thrombi by multiplane transesophageal echocardiography: interlaboratory comparative study.

BACKGROUND: Transesophageal echocardiography (TEE) is regarded as the method of choice for imaging left atrial appendage thrombi (LAAT). However, the interobserver variability among 2 independent echocardiographic laboratories in diagnosing LAAT by multiplane TEE has not yet been assessed. METHODS AND RESULTS: The videorecordings of 50 patients in atrial fibrillation (25 from each laboratory) were blindly reviewed by 1 experienced observer from each institution. LAAT were assessed as present, absent or questionable. Indications for TEE were: cardioversion (n=17), valve disease (n=13), endocarditis (n=12), or embolism (n=8). The prevalence of LAAT was 10% (observer 1) vs 12% (observer 2). A questionable LAAT was assessed in 6% vs 12% and a LAAT was excluded in 84% vs 76%, respectively. By head-to-head comparison, disagreement occurred in 11 cases (22%, kappa=0.5). Discrepant results were not related to the echocardiographic equipment. Problems occurred because of reverberation artifacts of the ridge between the left atrial appendage and left upper pulmonary vein (n=5), and in differentiating LAAT from spontaneous echocardiographic contrast (n=4) or an echogenic atrioventricular groove (n=1). The differentiation of pectinate muscles from LAAT was the reason for disagreement in only 1 case. Eliminating the category of questionable thrombi increased the kappa value to 0.65. In 5 patients undergoing cardiac surgery, both observers had agreed on the presence (n=1) or absence (n=4) of LAAT, and intraoperatively the results of TEE were confirmed. CONCLUSION: Even with multiplane TEE, interobserver variability among 2 independent echocardiographic laboratories for diagnosing LAAT remains high because of problems in differentiating LAAT from spontaneous echocardiographic contrast and reverberation artifacts.     

Detection of left atrial thrombi by echocardiography.

A group of 111 patients with mitral valve disease was studied by M-mode and two-dimensional echocardiography. Five left atrial thrombi were demonstrated, two of which had probably been the source of previous embolic events. Two-dimensional echocardiography was superior to M-mode in providing spatial orientation. Using multiple cross-sections the exact localisation and the size of the thrombus formation could be estimated. Thrombus localisations at the upper, lateral, and septal atrial walls, normally inaccessible to the single-beam technique, were successfully imaged. Even two-dimensional echocardiography, however, constitutes an imperfect method. By comparison with the findings at surgery only one-third of confirmed thrombi could be detected non-invasively. According to their localisation seven clots in the appendage were missed by the ultrasound method. One further thrombus fixed to the upper left atrial wall near the entrance of the upper pulmonary veins was also undetected by echocardiography. Despite these limitations, the information provided by echocardiography can be most helpful in patient management. M-mode, in combination with two-dimensional echocardiography, is therefore recommended in all patients with mitral stenosis before diagnostic or therapeutic procedures are undertaken.     

Patients with atrial fibrillation and dense spontaneous echo contrast at high risk a prospective and serial follow-up over 12 months with transesophageal echocardiography and cerebral magnetic resonance imaging

OBJECTIVES: We sought to assess the prognosis of patients with atrial fibrillation (AF) and dense spontaneous echo contrast (SEC) and to determine the incidence of cerebral embolism under continued oral anticoagulation. BACKGROUND: Patients with AF and dense SEC have an increased risk of cerebral embolism. However, there is little knowledge about the long-term fate and the rate of clinical silent cerebral embolism under continued oral anticoagulation. METHODS: Between 1998 and 2001, all consecutive patients with AF and dense SEC were included in the study. We performed serial and prospective transesophageal echocardiography, cranial magnetic resonance imaging, and clinical examinations during a period of 12 months. RESULTS: A total of 128 patients with dense SEC and AF were included. The control group consisted of 143 patients with faint SEC and AF. During the follow-up period, three patients (2%) had cerebral embolism with neurologic deficits. A total of eight patients (6%) died due to embolic events, and 19 (15%) patients had silent embolism, as documented on cerebral magnetic resonance imaging. Patients with an event had significantly lower left atrial appendage peak emptying velocities and more commonly had a history of previous thromboembolism and denser SEC, as compared with patients without an event. CONCLUSIONS: Patients with AF and dense SEC have a high likelihood of cerebral embolism (22%) and/or death, despite oral anticoagulation. Low peak emptying velocities of the left atrial appendage and dense SEC are independent predictors of an event.     

Pulmonary vein dilation in patients with atrial fibrillation: detection by magnetic resonance imaging

INTRODUCTION: The positive relationship between left atrial (LA) size and atrial fibrillation (AF) is well recognized; however, there is little information on the association of pulmonary vein (PV) diameter and AF. The purpose of this study was to investigate by magnetic resonance angiography the change of PV and LA size in patients with no history of AF, patients with paroxysmal AF (PAF), and patients with chronic AF (CAF). METHODS AND RESULTS: The study included 47 patients. Group I included 15 patients with normal sinus rhythm and no history of documented AF. Group II included 24 patients with drug-refractory PAF who underwent electrophysiologic study and radiofrequency ablation of PV foci. Group III included 8 patients with CAF who were converted to sinus rhythm by external electrical cardioversion. Age and concomitant heart diseases were similar among the three groups. We measured the diameter of each PV at its junction with the LA in addition to LA dimensions by gadolinium-enhanced magnetic resonance angiography with three-dimensional reconstruction. Significant dilation of both superior PVs (P < 0.01) and transverse diameter of LA (P < 0.01) was seen in the three groups. There were no significant changes of both inferior PVs, corrected PV (PV/LA) diameter, or longitudinal diameter of LA among the three groups. Only 28% patients showed arrhythmogenic foci from the largest PV. CONCLUSION: Significant dilation of both superior PVs with simultaneous LA enlargement was demonstrated i