- Open Access
Left atrial spontaneous echo contrast occurring in patients with low CHADS2 or CHA2DS2-VASc scores
Cardiovascular Ultrasound volume 18, Article number: 31 (2020)
Left atrial spontaneous echo contrast (LASEC) is common in patients with atrial fibrillation (AF), although scarce information exists on LASEC occurring in nonvalvular AF patients who have low thromboembolic risk scores. We therefore examined prevalence and determinants of LASEC under low CHADS2 or CHA2DS2-VASc scores in these patients.
Among 713 patients who underwent transesophageal echocardiography, 349 with a CHADS2 score < 2 (CHADS2 group) (93 women, mean age 65 years) and 221 with a CHA2DS2-VASc score < 2 (CHA2DS2-VASc group) (39 women, mean age 62 years) were separately examined for clinical and echocardiographic findings.
LASEC was found in 77 patients of CHADS2 group (22%) and in 41 of CHA2DS2-VASc group (19%). Multivariate logistic regression analysis, adjusted for several parameters including non-paroxysmal AF, LA enlargement (LA diameter ≥ 50 mm), left ventricular (LV) hypertrophy, and an elevated B-type natriuretic peptide (BNP) (BNP ≥200 pg/mL) revealed that for CHADS2 group, non-paroxysmal AF (Odds ratio 5.65, 95%CI 3.08–10.5, P < 0.001), BNP elevation (Odds ratio 3.42, 95%CI 1.29–9.06, P = 0.013), and LV hypertrophy (Odds ratio 2.26, 95%CI 1.19–4.28, P = 0.013) were significant independent determinants of LASEC, and that for CHA2DS2-VASc group, non-paroxysmal AF (Odds ratio 3.38, 95%CI 1.51–7.54, P = 0.003) and LV hypertrophy (Odds ratio 2.53, 95%CI 1.13–5.70, P = 0.025) were significant independent determinants of LASEC.
LASEC was present in a considerable proportion of patients with nonvalvular AF under low thromboembolic risk scores. Information on AF chronicity, BNP, and LV hypertrophy might help identify patients at risk for thromboembolism, although large-scale studies are necessary to confirm our observations.
There are numerous reports that left atrial spontaneous echo contrast (LASEC) is one of the strongest predictors of intraatrial thrombosis and subsequent thromboembolism [1,2,3,4]. Thromboembolic (TE) risk scores typified by CHADS2 and CHA2DS2-VASc have been used for the past decade to assess TE risk and to guide prophylactic anticoagulation in patients with nonvalvular atrial fibrillation (AF) . Studies on the association of transesophageal echocardiography (TEE) findings with CHADS2 or CHA2DS2-VASc scores in nonvalvular AF patients have shown a trend of which the greater score of CHADS2 or CHA2DS2-VASc, the more likely LASEC to be observed [6,7,8]; however, a certain number of patients are found to have LASEC despite low scores levels [6,7,8,9,10].
Generally, patients with non-paroxysmal AF who have chronic heart failure are in the predisposing condition to left atrial (LA) thrombus formation [11, 12], and particularly, those with increased LA size, left ventricular (LV) systolic dysfunction, and reduced LA appendage (LAA) velocity are most likely to be associated with LASEC and/or LA thrombus [13,14,15,16]. Scarce information, however, has existed on LASEC occurring in AF patients who have low TE risk scores [9, 10]. We therefore examined prevalence and determinants of the presence of LASEC in nonvalvular AF patients with low CHADS2 or CHA2DS2-VASc scores.
Materials and methods
We reviewed echocardiography reports, including digitized cine-loop images, and clinical charts on 713 patients with nonvalvular AF who underwent TEE between 2012 and 2018 in Osaka Medical College Hospital. TEE was performed in order to screen intracardiac thrombosis prior to pulmonary vein isolation procedure and/or direct cardioversion. There were 493 men and 220 women with a mean age of 67 years. Patients with rheumatic/degenerative mitral valve disease, congenital heart disease, and those in whom echocardiography and/or laboratory data considered to be important for the current analysis, particularly the B-type natriuretic peptide (BNP) and left ventricular (LV) ejection fraction, were lacking were excluded.
Figure 1 shows percentages of the presence of LASEC classified by CHADS2 and CHA2DS2-VASc scores in the 713 patients. Overall, the incidence of LASEC was found to increase accordingly with increases in CHADS2 and CHA2DS2-VASc scores (P < 0.001 for both). In the present study, following results were all drawn separately for the 2 groups: 349 patients with a CHADS2 score < 2 (CHADS2 group); and 221 with a CHA2DS2-VASc score < 2 (CHA2DS2-VASc group).
This study was approved by the Ethics Committee of Osaka Medical College with notification for guaranteed withdrawal of participants on the website providing means of “opt-out” (No. 2194–01).
Ultrasound machines used were Vivid 7 Dimension and Vivid E9 with the phased array probes for both transthoracic echocardiography and TEE (GE-Vingmed, Horten, Norway). LA diameter, and LV dimensions and wall thickness were measured under 2-dimensional image guidance. LV ejection fraction was obtained with the modified Simpson’s rule in the 2- and 4-chamber views, and an ejection fraction < 50% was defined as LV systolic dysfunction. LV mass was calculated using the Devereux formula, indexed by the body surface area to draw LV mass index. LV mass index ≥115 g/m2 in men and ≥ 95 g/m2 in women were considered as the presence of LV hypertrophy . The severity of mitral regurgitation was determined semi-quantitatively using color-flow mapping.
Standard multiplane TEE was performed using the same ultrasound machines with 6Tc and 6VT-D probes, respectively. The entire LA cavity was thoroughly examined for LASEC and LA thrombus with the gain setting being adjusted for optimal analysis. Attention was paid to differentiate the LAA thrombus from pectinate muscles . TEE images, on a routine basis, were stored as cine-loops for the subsequent analysis. The severity of LASEC was categorized as being absent, mild or severe on the basis of the system described by Daniel et al. and Beppu et al. [19, 20]. Mild LASEC was defined as being present if dynamic echoes were seen only with high gain, whereas severe LASEC was present if spontaneous contrast was noted even with low gain.
To evaluate reproducibility of LASEC severity, 30 cases that were randomly selected from our population, including severe (n = 4), mild (n = 12), and none (n = 14), were analyzed by 2 independent experienced observers. The concordance rate (κ) for the corresponding LASEC severity was 0.93.
LAA velocity was also obtained with the pulsed Doppler sample volume 1 to 2 cm positioned inside the LAA orifice, averaged over 3 and 5 consecutive cardiac cycles in case of patients in sinus rhythm and of those in AF, respectively.
Thromboembolic risk scores
CHADS2 score was calculated by giving 1 point each for congestive heart failure, hypertension, age ≥ 75 years, and diabetes, and 2 points for prior stroke or transient ischemic attack , and patients with a CHADS2 score < 2 were classified into the “low risk” category (CHADS2 group) [9, 22]. CHA2DS2-VASc score was calculated by giving 1 point each for congestive heart failure or LV systolic dysfunction (ejection fraction < 40%), hypertension, diabetes, vascular disease, age 65 to 74 years, and female gender, and 2 points for prior stroke or transient ischemic attack and for age ≥ 75 years , and patients with a CHA2DS2-VASc score < 2 were classified as “low risk” (CHA2DS2-VASc group) [9, 22].
Besides, we calculated HAS-BLED score (Hypertension, Abnormal Renal/Liver Function, Stroke, Bleeding History or Predisposition, Labile International Normalized Ratio [INR], Elderly, and Drugs/Alcohol) to assess the coagulation/bleeding status of the patients . We gave 0 point of “Labile INR” to all patients who had been taking DOACs.
Abnormalities of some clinical and echocardiographic parameters were determined as follows. Based on K/DOQI clinical practice guidelines , renal dysfunction was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73m2. BNP ≥200 pg/mL was considered clinically significant in accordance with the statement guideline by the Japanese Heart Failure Society (www.asas.or.jp/jhfs/english/outline/guidelines_20180822.html). LA enlargement and LAA dysfunction were defined as LA diameter ≥ 50 mm and LAA velocity < 20 cm/s, respectively [2, 25].
Continuous variables were expressed as mean ± SD and categorical variables as percentages. Comparisons of categorical variables were performed using the chi-square test or Fisher’s exact test as appropriate. Univariate and multivariate logistic regression analyses were introduced to predict determinants of LASEC for both CHADS2 and CHA2DS2-VASc groups. All analyses were performed using JMP Pro ver. 14.0 (SAS Institute, Cary, NC). A P values < 0.05 was considered significant.
Clinical and echocardiographic characteristics of the patient groups
Clinical characteristics of CHADS2 and CHA2DS2-VASc groups are presented in Table 1. With the exception of age and gender distribution, similar clinical features were found in both groups. In CHADS2 group, 128 patients (35%) had a CHA2DS2-VASc score ≥ 2 (Table 1). Among them, 88 patients (69%) had age 65–75 as an additional CHA2DS2-VASc risk component to congestive heart failure, hypertension, or diabetes; 54 (42%) had female gender; 20 (16%) had age ≥ 75; and 9 (7%) had vascular disease.
For both groups, nearly 10% of patients were shown to have significant LA enlargement and 5% to have reduced LV ejection fraction. LASEC was detected in 77 of CHADS2 group (22%) and in 41 of CHA2DS2-VASc group (19%). A small number of patients had LAA dysfunction (nearly 5% for both groups), and LA thrombus was found in only one patient, belonging to CHADS2 group. Figure 2 compares distribution of LASEC severity in CHADS2 and CHA2DS2-VASc groups in addition to a group of patients with CHA2DS2-VASc score ≥ 2, albeit included in CHADS2 group (n = 128). As shown, all groups included patients who had severe LASEC (4, 2, and 7%, respectively), and overall there was no statistically significant difference in LASEC severity between the groups (P = 0.11).
Determinants of LASEC
Table 2 shows the results of univariate logistic regression analysis for assessing determinants of the presence of LASEC for each group. It was found that for CHADS2 group, parameters except female gender were significantly related to LASEC whereas for CHA2DS2-VASc group, parameters except female gender and renal dysfunction were significantly related to LASEC.
Multivariate logistic regression analysis (Table 3), adjusted for parameters that were of statistical significance in the univariate analysis (P < 0.05), demonstrated that for CHADS2 group, non-paroxysmal AF, BNP elevation, and LV hypertrophy were significant independent determinants of LASEC, and that for CHA2DS2-VASc group, non-paroxysmal AF and LV hypertrophy were significant independent determinants of LASEC.
Figure 3 compares contribution of clinical and echocardiographic parameters to LASEC detection, which is based on the multivariate analysis as in Table 3, with an additional covariate of “LAA velocity <20 cm/s” being included into the model. It was found that for both CHADS2 and CHA2DS2-VASc groups, LAA velocity < 20 cm/s and non-paroxysmal AF were exceeding a LogWorth value of 2, which is identical to P < 0.01.
It was demonstrated in our population that a considerable proportion of patients with low TE risk scores had LASEC, that clinical and echocardiographic parameters did not differ as much between CHADS2 and CHA2DS2-VASc groups, and that on the multivariate analysis, LASEC occurrence was related to non-paroxysmal AF, BNP elevation (BNP ≥200 pg/mL), or LV hypertrophy.
Previous studies on LASEC and thromboembolic risk scores
There are several reports on the relationship between TEE findings and TE risk scores. In most cases, the prevalence of LASEC and/or LAA dysfunction was shown to increase accordingly with increases in CHADS2 and CHA2DS2-VASc scores [6,7,8]. One explanation for this association is that elevation of TE risk scores is more likely to be associated with cardiac conditions predisposed to thrombus formation such as LA enlargement and LV systolic dysfunction [14,15,16]. In a different view point, increases in CHADS2 and CHA2DS2-VASc scores may enhance production of various inflammatory cytokines exerting as prothrombotic substrates [26, 27].
LASEC occurrence under low TE risk scores
There are several studies on LASEC occurring under low TE risk scores [6, 9, 10, 15]. We observed that approximately 20% of the low TE risk score patients had LASEC, the number of which was similar to that reported previously [6, 15]. Although our data suggest that AF persistence and LV hypertrophy are associated with LASEC production, the pathological basis for SEC is quite complex, with various factors being interplay ; in fact, some investigators failed to find relationship between TE risk scores, LASEC, and LAA velocity .
Yao et al. reported that an elevated plasma homocysteine could be a risk of LA thrombus in nonvalvular AF patients . Homocysteine seems to accelerate arterial and venous thrombosis through biological damage to vascular endothelium by generating oxidative stress, reducing NO-production, and inducing inflammatory response . Kimura et al. used computed tomography for 3-dimesinal construction of the atrium to assess relationship between LAA morphologies (cactus, cauliflower, chicken-wing, and windsock) and a risk of stroke. They found that the cauliflower type was mostly related to the prior stroke especially in those with low CHADS2 scores .
LASEC occurring in our population appears to result from the difference in individual TE risk components (hypertension, diabetes, etc.), rather than the difference in the scores themselves. This might be substantiated by the finding in Table 4 that congestive heart failure was more common in patients with LASEC than those without, whereas other TE risk components such as hypertension did not show such differences. Congestive heart failure is a syndrome that is usually associated with cardiac changes leading to the development of LASEC [11,12,13,14,15].
The finding of LV hypertrophy being stratified as a predictor of LASEC better than other parameters such as LA diameter and LV ejection fraction was surprising. This may be relate, for one thing, to the fact that LV hypertrophy is often associated with LA enlargement , potentially leading to the occurrence of LASEC; in fact, for CHA2DS2-VASc group, 10 patients (21%) with LV hypertrophy had LA enlargement, and 9 (41%) with LA enlargement had LASEC. In addition, the relatively limited number of patients who had either LA diameter ≥50 mm or LV ejection fraction <50% (Table 1) might exclusively contributed to LV hypertrophy that emerged as a significant correlate of LASEC.
One message in the present study is to determine what parameters, except TEE ones, would be responsible for LASEC that occurs in patients with low TE risk scores. The exception of TEE parameters was based on the fact that TEE is a semi-invasive procedure with its application as a screening tool being limited. As shown in Fig. 3, “LAA velocity <20 cm/s” and “non-paroxysmal AF” are comparable in contributing to LASEC detection in both groups. This suggests that AF chronicity, even without support from TEE, becomes the best marker of LASEC occurrence, and particularly, this finding would be supporting the recommendation by Puwanant et al. that a screening TEE should be performed in patients with a CHADS2 score of 0 whose AF is persistent .
The present study is subject to the limitations inherent to a single center study. All clinical and echocardiographic data were obtained retrospectively and thus a certain kind of misclassification might be inevitable. Another limitation was that the duration of AF and the adequacy of anticoagulation could not be reliably extracted from the patient records, which might result in overestimation of the number of non-paroxysmal AF patients. However, LASEC represents not only a history of AF but also condition of the atrial tissue [31, 32], and most of our patients were on anticoagulation that was religiously monitored for hemorrhagic status with reference to the INR. Finally, this study consists of a small number of patients and thus our findings may not be generalized to other population.
We investigated clinical and echocardiographic parameters that would determine LASEC formation on nonvalvular AF patients with low CHADS2 or CHA2DS2-VASc scores. About 20% of the patients were found to be associated with LASEC. With results of the multivariate analysis taken into account, information on AF chronicity, BNP, and LV hypertrophy might help identify patients at risk for thromboembolism, although large-scale studies are necessary to confirm our observations.
Availability of data and materials
All data generated or analyzed during this study are included in this published article [and its supplementary information files].
B-type natriuretic peptide
Estimated glomerular filtration rate
International normalized ratio
Left atrial appendage
Left atrial spontaneous echo contrast
Leung DY, Black IW, Cranney GB, Hopkins AP, Walsh WF. Prognostic implications of left atrial spontaneous echo contrast in nonvalvular atrial fibrillation. J Am Coll Cardiol. 1994;24:755–62. https://doi.org/10.1016/0735-1097(94)90025-6.
Transesophageal echocardiographic correlates of thromboembolism in high-risk patients with nonvalvular atrial fibrillation. The stroke prevention in atrial fibrillation investigators committee on echocardiography. Ann Intern Med. 1998;128:639–47.
Black IW, Hopkins AP, Lee LC, Walsh WF. Left atrial spontaneous echo contrast: a clinical and echocardiographic analysis. J Am Coll Cardiol. 1991;18:398–404. https://doi.org/10.1016/0735-1097(91)90592-w.
Miyazaki S, Ito T, Suwa M, Nakamura T, Kobashi A, Kitaura Y. Role of transesophageal echocardiography in the prediction of thromboembolism in patients with chronic nonvalvular atrial fibrillation. Jpn Circ J. 2001;65:874–8. https://doi.org/10.1253/jcj.65.874.
Camm AJ, Kirchhof P, Lip GY, Schotten U, Savelieva I, Ernst SV, et al. Guidelines for the management of atrial fibrillation: the task force for the management of atrial fibrillation of the European Society of Cardiology (ESC). Eur Heart J. 2010;31:2369–429. https://doi.org/10.1093/eurheartj/ehq278.
Puwanant S, Varr BC, Shrestha K, Hussain SK, Tang WH, Gabriel RS, et al. Role of the CHADS2 score in the evaluation of thromboembolic risk in patients with atrial fibrillation undergoing transesophageal echocardiography before pulmonary vein isolation. J Am Coll Cardiol. 2009;54:2032–9. https://doi.org/10.1016/j.jacc.2009.07.037.
Zhang E, Liu T, Li Z, Zhao J, Li G. High CHA2DS2-VASc score predicts left atrial thrombus or spontaneous echo contrast detected by transesophageal echocardiography. Int J Cardiol. 2015;184:540–2. https://doi.org/10.1016/j.ijcard.2015.02.109.
Willens HJ, Gómez-Marín O, Nelson K, DeNicco A, Moscucci M. Correlation of CHADS2 and CHA2DS2-VASc scores with transesophageal echocardiography risk factors for thromboembolism in a multiethnic United States population with nonvalvular atrial fibrillation. J Am Soc Echocardiogr. 2013;26:175–84. https://doi.org/10.1016/j.echo.2012.11.002.
Yao Y, Shang MS, Gao LJ, Zhao JH, Yang XH, Liu T. Elevated homocysteine increases the risk of left atrial/left atrial appendage thrombus in non-valvular atrial fibrillation with low CHA2DS2-VASc score. Europace. 2018;20:1093–8. https://doi.org/10.1093/europace/eux189.
Yoshida N, Okamoto M, Hirao H, Nanba K, Kinoshita H, Matsumura H, et al. Role of transthoracic left atrial appendage wall motion velocity in patients with persistent atrial fibrillation and a low CHADS2 score. J Cardiol. 2012;60:310–5. https://doi.org/10.1016/j.jjcc.2012.05.007.
Doukky R, Gage H, Nagarajan V, Demopoulos A, Cena M, Garcia-Sayan E, et al. B-type natriuretic peptide predicts left atrial appendage thrombus in patients with nonvalvular atrial fibrillation. Echocardiography. 2013;30:889–95. https://doi.org/10.1111/echo.12169.
Iwakura K, Okamura A, Koyama Y, Date M, Higuchi Y, Inoue K, et al. Effect of elevated left ventricular diastolic filling pressure on the frequency of left atrial appendage thrombus in patients with nonvalvular atrial fibrillation. Am J Cardiol. 2011;107:417–22. https://doi.org/10.1016/j.amjcard.2010.09.042.
Fatkin D, Kelly RP, Feneley MP. Relations between left atrial appendage blood flow velocity, spontaneous echocardiographic contrast and thromboembolic risk in vivo. J Am Coll Cardiol. 1994;23:961–9. https://doi.org/10.1016/0735-1097(94)90644-0.
Black IW, Chesterman CN, Hopkins AP, Lee LC, Chong BH, Walsh WF. Hematologic correlates of left atrial spontaneous echo contrast and thromboembolism in nonvalvular atrial fibrillation. J Am Coll Cardiol. 1993;21:451–7. https://doi.org/10.1016/0735-1097(93)90688-w.
Rader VJ, Khumri TM, Idupulapati M, Stoner CN, Magalski A, Main ML. Clinical predictors of left atrial thrombus and spontaneous echocardiographic contrast in patients with atrial fibrillation. J Am Soc Echocardiogr. 2007;20:1181–5. https://doi.org/10.1016/j.echo.2007.02.010.
Siostrzonek P, Koppensteiner R, Gössinger H, Zangeneh M, Heinz G, Kreiner G, et al. Hemodynamic and hemorheologic determinants of left atrial spontaneous echo contrast and thrombus formation in patients with idiopathic dilated cardiomyopathy. Am Heart J. 1993;125(2 Pt 1):430–4. https://doi.org/10.1016/0002-8703(93)90022-2.
Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, et al. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. Eur Heart J Cardiovasc Imaging. 2015;16:233–70. https://doi.org/10.1093/ehjci/jev014.
Orsinelli DA, Pearson AC. Usefulness of multiplane transesophageal echocardiography in differentiating left atrial appendage thrombus from pectinate muscles. Am Heart J. 1996;131:622–3. https://doi.org/10.1016/s0002-8703(96)90553-0.
Daniel WG, Nellessen U, Schröder E, Nonnast-Daniel B, Bednarski P, Nikutta P, et al. Left atrial spontaneous echo contrast in mitral valve disease: an indicator for an increased thromboembolic risk. J Am Coll Cardiol. 1988;11:1204–11. https://doi.org/10.1016/0735-1097(88)90283-5.
Beppu S, Nimura Y, Sakakibara H, Nagata S, Park YD, Izumi S. Smoke-like echo in the left atrial cavity in mitral valve disease: its features and significance. J Am Coll Cardiol. 1985;6:744–9. https://doi.org/10.1016/S0735-1097(85)80476-9.
Eckman MH, Singer DE, Rosand J, Greenberg SM. Moving the tipping point: the decision to anticoagulate patients with atrial fibrillation. Circ Cardiovasc Qual Outcomes. 2011;4:14–21. https://doi.org/10.1161/CIRCOUTCOMES.110.958108.
Clark CB, Telles Garcia NA, Hackett Renner C, Ryan SM. Correlation of left atrial appendage ejection velocities with the CHADS2 and CHA2DS2-VASc scores. Echocardiography. 2016;33(8):1195–201. https://doi.org/10.1111/echo.13228.
Lip GY, Frison L, Halperin JL, Lane DA. Comparative validation of a novel risk score for predicting bleeding risk in anticoagulated patients with atrial fibrillation. J Am Coll Cardiol. 2011;57:173–80. https://doi.org/10.1016/j.jacc.2010.09.024.
K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis. 2002;39(2 Suppl 1):S1–266.
Zabalgoitia M, Halperin JL, Pearce LA, Blackshear JL, Asinger RW, Hart RG. Transesophageal echocardiographic correlates of clinical risk of thromboembolism in nonvalvular atrial fibrillation. Stroke prevention in atrial fibrillation III investigators. J Am Coll Cardiol. 1998;31:1622–6. https://doi.org/10.1016/s0735-1097(98)00146-6.
Maehama T, Okura H, Imai K, Yamada R, Obase K, Saito K, et al. Usefulness of CHADS2 score to predict C-reactive protein, left atrial blood stasis, and prognosis in patients with nonrheumatic atrial fibrillation. Am J Cardiol. 2010;106:535–8. https://doi.org/10.1016/j.amjcard.2010.03.067.
Yashiro Y, Arimoto T, Hashimoto N, Tamura H, Iwayama T, Ishigaki D, et al. Predictors of left atrial coagulation activity among paroxysmal atrial fibrillation patients. Circ J. 2015;79(1):61–9. https://doi.org/10.1253/circj.CJ-14-0630.
Ito T, Suwa M. Left atrial spontaneous echo contrast: relationship with clinical and echocardiographic parameters. Echo Res Pract. 2019;6:R65–73. https://doi.org/10.1530/ERP-18-0083.
Kimura T, Takatsuki S, Inagawa K, Katsumata Y, Nishiyama T, Nishiyama N, et al. Anatomical characteristics of the left atrial appendage in cardiogenic stroke with low CHADS2 scores. Heart Rhythm. 2013;10:921–5. https://doi.org/10.1016/j.hrthm.2013.01.036.
Seko Y, Kato T, Haruna T, Izumi T, Miyamoto S, Nakane E, et al. Association between atrial fibrillation, atrial enlargement, and left ventricular geometric remodeling. Sci Rep. 2018;8:6366. https://doi.org/10.1038/s41598-018-24875-1.
Agmon Y, Khandheria BK, Gentile F, Gentile F, Seward JB. Echocardiographic assessment of the left atrial appendage. J Am Coll Cardiol. 1999;34:1867–77. https://doi.org/10.1016/s0735-1097(99)00472-6.
Mitusch R, Garbe M, Schmucker G, Schwabe K, Stierle U, Sheikhzadeh A, et al. Relation of left atrial appendage function to the duration and reversibility of nonvalvular atrial fibrillation. Am J Cardiol. 1995;75:944–7. https://doi.org/10.1016/s0002-9149(99)80695-x.
No funding for the current study was received.
Ethics approval and consent to participate
This study was approved by the ethics review board of Osaka Medical College with notification for guaranteed withdrawal of participants on the website providing means of “opt-out” (No. 2194–01).
Consent for publication
Our manuscript does not contain any individual person’s data in any form (including individual details, images or videos).
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Akamatsu, K., Ito, T., Ozeki, M. et al. Left atrial spontaneous echo contrast occurring in patients with low CHADS2 or CHA2DS2-VASc scores. Cardiovasc Ultrasound 18, 31 (2020). https://doi.org/10.1186/s12947-020-00213-2
- Atrial fibrillation
- Spontaneous echo contrast
- Transesophageal echocardiography
- CHADS2 score
- CHA2DS2-VASc score