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     

经食管超声左心耳参数与心房颤动患者左心耳血栓和/或自发显影的关系

目的探讨经食管超声左心耳(LAA)参数与心房颤动(简称房颤)患者LAA血栓和/或自发显影(SEC)是否存在相关性。方法选取在本院心血管内科收治并接受经食管超声心动图(TEE)检查发现LAA血栓和/或SEC的房颤患者34例为SEC组;同时,同期以1∶2的比例随机选取接受TEE检查但并未发现LAA血栓和/或SEC的房颤患者68例为非SEC组。收集患者既往病史资料,并测定其左房前后径(LAD)、左室射血分数(LVEF)和左心耳开口宽度(LAAW)、左心耳长度(LAAL)、左心耳血流排空速度(LFEV)、左心耳血流充盈速度(LFFV)、左心耳射血分数(LAAEF)等指标。多因素Logistic回归分析房颤患者LAA血栓和/或SEC的独立危险因素。结果两组之间年龄、房颤类型(持续性房颤比例)、脑卒中/短暂脑缺血发作(TIA)病史、CHA_2DS_2-VASc评分、LAD、LAAW、LAAL、LVEF、LFEV、LFFV、LAAEF差异有统计学意义。调整其他危险因素,通过多因素Logistic回归分析发现,既往脑卒中/TIA(OR 22.894;95%CI 1.883~278.418;P=0.014),更大的LAAW(OR 1.205;95%CI 1.008~1.441;P=0.040)、LAAL(OR 1.203;95%CI 1.039~1.394;P=0.014)及更低的LAAEF(OR 0.964;95%CI 0.929~0.999;P=0.047)是房颤患者LAA血栓和/或SEC的独立危险因素。结论房颤患者LAA结构增大及较低的LAAEF提示LAA血栓和/或SEC的可能性增大。     

Quantification of left atrial appendage spontaneous echo contrast in patients with chronic nonalvular atrial fibrillation.

OBJECTIVES: The left atrial (LA) appendage is the most common site of thrombus formation in patients with atrial fibrillation, and integrated backscatter allows the quantiative assessment of LA spontaneous echo contrast (SEC). Integrated backscatter was used to examine the significance of measuring appendage SEC, specifically in relation to echocardiographic variables implying thromboembolism, in patients with chronic nonvalvular atrial fibrillation. METHODS: Fifty-two patients with chronic nonvalvular atrial fibrillation and no prior anticoagulant therapy (35 men, 17 women, mean age 66 +/- 7 years) underwent transesophageal echocardiography with integrated backscatter analysis. The LA and LA appendage integrated backscatter intensity were measured with the regions of interest placed in the LA cavity and the appendage, respectively. The integrated backscatter intensity values for these two chambers (corrected "LA" and "LA appendage" integrated backscatter intensity, respectively) were corrected using values from the left ventricular cavity. RESULTS: The LA appendage integrated backscatter intensity values were available in 44 patients (85%). Overall, the corrected LA appendage integrated backscatter intensity was significantly increased compared with the corrected LA integrated backscatter intensity (2.8 +/- 2.2 vs 2.0 +/- 1.8 dB, p < 0.001). The corrected LA appendage integrated backscatter intensity was inversely correlated with the LA appendage velocity (r = -0.37, p < 0.05), but not with the LA dimension, appendage size, or left ventricular function. The corrected appendage integrated backscatter intensity (4.5 +/- 2.3 vs 2.4 +/- 1.9 dB, p < 0.01) and LA integrated backscatter intensity (3.2 +/- 2.1 vs 1.7 +/- 1.7 dB, p < 0.05) were higher in patients who had LA appendage thrombus (n = 8) than those who did not. With the corrected appendage integrated backscatter intensity set at > or = 2.5 dB, the sensitivity for the presence of appendage thrombus was 88% and the specificity was 64%. CONCLUSIONS: Patients with chronic nonvalvular atrial fibrillation had a denser SEC in the LA appendage compared with SEC in the main LA cavity. The severity of the appendage SEC was influenced by the LA appendage function rather than its size. Quantification of SEC in the appendage, rather than main LA cavity, was more valuable for assessing embolic potential.     

Prevalence and clinical significance of left atrial spontaneous echo contrast detected by transesophageal echocardiography

The prevalence and clinical significance of left atrial spontaneous echo contrast (SEC) were studied in patients undergoing transesophageal echocardiography (TEE). The study group included 290 consecutive patients (186 male and 104 female, aged 17-86 years, mean age 56.1 +/- 12.8 years). Left atrial SEC was found in 50 (17.2%) patients, and was significantly associated with atrial fibrillation, mitral stenosis, absence of mitral regurgitation, and left atrial dimension. Atrial fibrillation was recorded in 44 (88%) patients, mitral stenosis or mitral valve replacement in 21 (42%) patients, and left atrial thrombus or previous embolism in 23 (46%) patients with SEC. Univariate analysis showed a significant association between the presence of SEC and atrial fibrillation, mitral stenosis or mitral valve replacement, and left atrial size. Multivariate analysis showed the presence of left atrial SEC and atrial fibrillation to be independent factors for thrombus formation and/or thromboembolism. Since left atrial SEC associated with atrial fibrillation, left atrial enlargement, mitral stenosis, or mitral valve prosthesis was found in 17.2% of patients undergoing TEE, it might be considered a marker of left atrial thrombus or previous thromboembolism.     

Predictors of left atrial spontaneous echo contrast and thrombi in patients with mitral stenosis and atrial fibrillation

The purpose of this study was to investigate the independent factors associated with the presence of left atrial (LA) spontaneous echo contrast (SEC) and thromboembolic events in patients with mitral stenosis (MS) in chronic atrial fibrillation (AF). Factors independently associated with LASEC, thrombi, and embolic events have been mainly investigated in patients with nonvalvular AF or inhomogeneous populations with rheumatic heart disease. Transesophageal and transthoracic echo studies were performed in 129 patients with MS in chronic AF. Previous embolic events were documented in 45 patients, 20 of them within 6 months, and 65 patients were receiving long-term anticoagulation. The intensity of LASEC and mitral regurgitation, the presence of thrombi and active LA appendage flow (peak velocities > or = 20 cm/s), and LA volume as well as other conventional echo-Doppler determinations were investigated in every patient. The prevalences of significant LASEC (degrees 3+ and 4+), thrombus, active LA appendage flow, and significant mitral regurgitation (>2+) were: 52% (67 patients), 29.5% (38 patients), 32% (41 patients), and 36% (47 patients), respectively. Multivariate analysis showed that decreasing mitral regurgitation severity, absence of active LA appendage flow, and mitral valve area were the independent correlates of LASEC (odds ratio [OR] 3.7, 5.4, and 0.17, respectively; all p <0.02). Active LA appendage flow and anticoagulant therapy were associated negatively, whereas the severity of LASEC was associated positively with the finding of LA thrombus (OR 9.6, 3.9, and 1.6, respectively; all p <0.05). The intensity of LASEC and previous anticoagulant therapy (OR 1.74 and 4.5, respectively; p <0.005) were the independent covariates of thrombi and/or recent embolic events. In conclusion, the severity of mitral regurgitation and lack of active LA appendage flow were, respectively, the strongest independent correlates of significant LASEC and thrombus in patients with MS in chronic AF. LASEC remains the cardiac factor most strongly associated with thrombus and/or recent embolic events in these patients.     

Left atrial thrombi and spontaneous echo contrast in patients with atrial fibrillation

Herz - Atrial fibrillation is associated with a&nbsp;high risk for thromboembolic events. Thrombi in the left atrial appendage and spontaneous echo contrast (SEC) correlate positively with this...     

Effect of batroxobin on spontaneous echo contrast and hemorheology in left atrial appendage in atrial fibrillation assessed by transesophageal echocardiograpy.

Controversy exists regarding the effect of defibrination on spontaneous echo contrast and flow dynamics in left atrial appendage (LAA) in atrial fibrillation. We aimed to investigate the effect of batroxobin, which decreases plasma fibrinogen level, on the echo intensity of spontaneous echo contrast in LAA. In 36 patients with atrial fibrillation (duration 7 +/- 4 years), transesophageal echocardiography was performed at baseline and 24 hours after batroxobin administration (0.2 U/kg). At the orifice of the LAA, integrated backscatter of echo contrast and peak velocity of LAA emptying flow were measured. Plasma fibrinogen and whole blood viscosity were also measured. Fibrinogen and viscosity were significantly lower after batroxobin administration (96 +/-38 mg/dl and 4.35 +/- 0.56 cp) than those at baseline (320 +/- 61 mg/dl and 4.71 +/- 0.61 cp, both p <0.001). A significant positive correlation between changes in plasma fibrinogen and whole blood viscosity (r = 0.49, p = 0.002) was shown. The integrated backscatter significantly decreased from 14 +/- 3 to 12 +/- 3 decibels after batroxobin (p <0.001), and the changes in integrated backscatter and plasma fibrinogen was significantly correlated. Therefore, batroxobin administration improved blood rheology and decreased blood cell aggregation, which are effective in preventing left atrial thrombus formation.     

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.     

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.     

Identification of right atrial thrombi using transoesophageal echocardiography

The in vivo diagnosis of right atrial thrombus is difficultby transthoracic echocardiography and it is likely that smallthrombi are underdiagnosed using this approach. Transoesophagealechocardiography provides an unobstructed view of cardiac structuresand the great vessels. In this report we describe the findingsin five patients with right atrial thrombi that illustrate thepotential usefulness of transoesophageal echocardiography forboth the initial diagnosis and the subsequent management ofthese patients.     

Clinical implications of left atrial spontaneous echo contrast in nonrheumatic atrial fibrillation.

The prevalence and clinical significance of left atrial (LA) spontaneous echo contrast were investigated in 103 consecutive patients with chronic nonrheumatic atrial fibrillation (AF) using transesophageal echocardiography. LA spontaneous echo contrast was visualized in 25 of 103 patients (24.3%). Age, sex, LA diameter, left ventricular diastolic and systolic dimensions, left ventricular ejection fraction, and the percentage of lone AF were not significantly different between patients with and without LA spontaneous echo contrast; however, those with LA spontaneous echo contrast were less likely to have moderate or severe mitral regurgitation. LA thrombi were observed in 7 patients (6.8%), and all 7 thrombi were found in the atria with spontaneous echo contrast. History of cerebral ischemia or peripheral embolism, or both, was significantly more frequent in patients with than without LA spontaneous echo contrast (84 vs 18%; p less than 0.001). The presence of LA spontaneous echo contrast was highly specific (94%) and predictive for thromboembolic events (positive and negative predictive values of 84 and 82%, respectively). Thus, transesophageal echo-detected LA spontaneous echo contrast is frequently found in patients with chronic nonrheumatic AF. This phenomenon may represent a precursor of thrombus formation, and its presence is associated with an increased thromboembolic risk.     

Prediction of left atrial appendage thrombi in non-valvular atrial fibrillation.

AIMS: There is little knowledge about the predictors of left atrial appendage (LAA) thrombi in non-valvular atrial fibrillation (NVAF). We investigated the ability of D-dimer to predict LAA thrombi. METHODS AND RESULTS: In this study, 925 patients with NVAF were enrolled. At the time of transoesophageal echocardiography (TEE), D-dimer levels were measured simultaneously. Significant independent predictors of LAA thrombi were the presence of congestive heart failure [odds ratio (OR) 3.10, 95% confidence interval (CI) 1.77-5.50, P < 0.0001), a history of recent embolic events (OR 3.39, 95% CI 1.90-6.04, P < 0.0001), and D-dimer levels (OR 97.6, 95% CI 17.3-595.8, P < 0.0001). Receiver operating characteristic analysis yielded an optimal cutoff value of 1.15 microg/mL for D-dimer to detect LAA thrombi. LAA thrombi were detected in 21.8% of patients with higher D-dimer values, whereas it was detected in only 3.1% of patients with lower D-dimer values. D-dimer cutoff level of 1.15 microg/mL had a negative predictive value of 97% for identifying LAA thrombi. CONCLUSION: In patients with NVAF, D-dimer may be helpful for predicting the absence of LAA thrombi. D-dimer level was clinically useful to guide the management of patients with NVAF, especially for those complicated with congestive heart failure and/or recent embolic events.     

Association of follow-up change of left atrial appendage blood flow velocity with spontaneous echo contrast in nonrheumatic atrial fibrillation

STUDY OBJECTIVES: To evaluate the time-related change of left atrial (LA) appendage flow velocity in chronic atrial fibrillation (AF) by follow-up transesophageal echocardiography (TEE) and to investigate its association with the occurrence of LA spontaneous echo contrast. DESIGN: Prospective follow-up study. SETTING: University-based, tertiary referral medical center. PATIENTS: Forty-seven patients with chronic nonrheumatic AF. INTERVENTIONS: All studied patients underwent both a baseline and follow-up TEE during a mean period of 13 +/- 7 months. Measurements and results: Baseline TEE revealed that LA spontaneous echo contrast was present in 28 patients (group 1) and was absent in 19 patients (group 2). The LA appendage flow velocity profiles at baseline were significantly lower in group 1 than in group 2; on follow-up, the appendage flow velocities decreased significantly in group 2, but were not significantly changed in group 1. Follow-up TEE revealed that spontaneous echo contrast was persistent in all group 1 patients. In group 2, LA spontaneous echo contrast was newly observed in 9 patients (group 2A) but was persistently absent in 10 patients (group 2B). In group 2A, all of the LA appendage flow velocity profiles decreased significantly at the follow-up study. In group 2B, however, only LA appendage inflow velocity integral showed significant decrease on follow-up; there were no significant changes in LA appendage outflow velocity indexes and peak inflow velocity. CONCLUSIONS: LA appendage flow velocity may decrease with time in some patients with AF, and this change is associated with a new occurrence of LA spontaneous echo contrast. For patients without LA spontaneous echo contrast, serial follow-up of the LA appendage flow velocity profiles may be useful for predicting future development of spontaneous echo contrast. Once LA spontaneous echo contrast occurs in AF patients, it tends to persist with time and the LA appendage is usually under a persistently low flow state.     

Integrated backscatter for quantification of left atrial spontaneous echo contrast

Objectives. This study was designed to develop a quantitative method of spontaneous echo contrast (SEC) assessment using integrated backscatter and to compare integrated backscatter SEC measurement with independent qualitative grades of SEC and clinical and echocardiographic predictors of thromboembolism.Background. Left atrial SEC refers to dynamic swirling smoke-like echoes that are associated with low flow states and embolic events and have been graded qualitatively as mild or severe.Methods. We performed transesophageal echocardiography in 43 patients and acquired digital integrated backscatter image sequences of the interatrial septum to internally calibrate the left ventricular cavity and left atrial cavity under different gain settings. Patients were independently assessed as having no, mild or severe SEC. We compared intensity of integrated backscatter in the left atrial cavity relative to that in the left ventricular as well as to the independently assessed qualitative grades of SEC. Fourier analysis characterized the temporal variability of SEC. The integrated backscatter was compared with clinical and echocardiographic predictors of thromboembolism.Results. The left atrial cavity integrated backscatter intensity of the mild SEC subgroup was 4.7 dB higher than that from the left ventricular cavity, and the left atrial intensity of the severe SEC subgroup was 12.5 dB higher than that from the left ventricular cavity. The left atrial cavity integrated backscatter intensity correlated well with the qualitative grade. Fourier transforms of SEC integrated backscatter sequences revealed a characteristic dominant low frequency/high amplitude spectrum, distinctive from no SEC. There was a close relationship between integrated backscatter values and atrial fibrillation, left atrial size, left atrial appendage flow velocities and thrombus.Conclusions. Integrated backscatter provides an objective quantitative measure of SEC that correlates well with qualitative grade and is closely associated with clinical and echocardiographic predictors of thromboembolism. The relationship between integrated backscatter measures and cardioembolic risk will be defined in future multicenter studies.     

111In-labeled platelet scintigraphy and two-dimensional echocardiography for detection of left atrial appendage thrombi. Studies in a new canine model

111In-labeled platelet scintigraphy and two-dimensional echocardiography were performed in 40 dogs to determine the ability of the two techniques to detect left atrial appendage thrombi. Thrombi were induced in 33 dogs that were classified into two groups, "acute" or "chronic," according to the time of labeled-platelet injection after thrombus induction. In the acute group (17 dogs), platelets were injected 24 hours after thrombus induction. In the chronic group (16 dogs), platelets were injected 4-8 days after thrombus induction. "Sham" thoracotomies were performed on seven additional control dogs who did not receive thrombin injections. Analog and blood pool-corrected 111In-labeled platelet scintigraphy images were obtained 4-72 hours later. Closed-chest two-dimensional echocardiography was performed before thoracotomy and repeated at the time of scintigraphy. The location and size of each thrombus were verified at autopsy. Two-dimensional echocardiography detected three of 17 acute (mean volume, 1.2 +/- 1.0 cc) and three of 10 chronic (mean volume, 0.4 +/- 0.3 cc; p less than 0.025) left atrial appendage thrombi. 111In-labeled platelet scintigraphy detected all 17 acute thrombi but only two of 10 chronic thrombi. The measured radioactivity levels of the excised thrombi were 1,949 +/- 1,665 cpm/clot/dose in group 1 and 228 +/- 213 cpm/clot/dose in group 2 (p less than 0.005). In this model, 111In-labeled platelet scintigraphy was able to detect acute left atrial appendage thrombi that could not be identified by two-dimensional echocardiography. Both techniques showed poor sensitivity for detection of chronic thrombi. The decline in sensitivity of 111In-labeled platelet scintigraphy for detection of older thrombi is probably due to diminished labeled-platelet incorporation.