Cardiovascular Revascularization Medicine 16 (2015) 12–14
Contents lists available at ScienceDirect
Cardiovascular Revascularization Medicine
Prevalence and predictors of left atrial thrombus in patients with atrial fibrillation: is transesophageal echocardiography necessary before cardioversion? Rahul Malik a, Daniel M. Alyeshmerni b, Zuyue Wang a, Steven A. Goldstein a, Rebecca Torguson a, Joseph Lindsay a, Ron Waksman a,⁎, Itsik Ben-Dor a a b
Division of Cardiology, Washington Hospital Center, Washington, DC Division of Cardiology, University of Michigan Health System, Ann Arbor, MI
a r t i c l e
i n f o
Article history: Received 17 December 2014 Accepted 17 December 2014 Keywords: Thrombus Atrial fibrillation Left atrial thrombus
a b s t r a c t Background: Systemic embolization threatens patients with atrial fibrillation (AF). The risk is enhanced at the time of cardioversion. Transesophageal echocardiography (TEE) prior to cardioversion to screen for left atrial thrombus (LAT), a marker of high risk for embolization, is recommended for many patients with AF. Objective: To determine clinical and echocardiographic factors associated with LAT formation in AF. Methods: Data from 600 consecutive patients with AF undergoing TEE prior to cardioversion for the detection of LAT were analyzed. Clinical, laboratory, and echocardiographic parameters were abstracted from the clinical record. Results: TEE identified LAT in 70 (11.6%) and dense (LA) spontaneous echo contrast (SEC) in 156 (26%). Baseline characteristics and echocardiographic parameters of patients with or without LAT are compared. A prior myocardial infarction, 21 (29.4 %) vs. 31 (5.8), (p b 0.001); hypertension, 60 (85.7%) vs. 386 (72.8), (p 0.02); CHADS 2 ≥ 2, 56 (80%) vs. 308 (58.1%), (p b 0.001) prevalence was higher in patients with LAT. Patients with LAT had lower ejection fraction 38.2 ± 15.6 vs. 46.2 ± 14.5, (p b 0.001); higher LA diameter 4.98 ± 0.7 vs. 4.52 ± 0.7, (p b 0.001); dense LA SEC 44 (62.8) vs. 112 (21.1), (p b 0.001); and low LA appendage emptying velocity 21.7 ± 12.9 vs. 37.5 ± 19.4, (p b 0.001). Multivariate analysis was done, and it revealed that low LA emptying velocity had the strongest independent association with LAT (HR 0.89 [CI 0.83–0.96], p value b0.001. Conclusion: LAT is not an uncommon finding of AF patients prior to cardioversion. The current practice of TEE examination may be justified since neither clinical nor routine 2D echo examinations reliably identify LAT. © 2014 Published by Elsevier Inc.
1. Introduction
2. Methods
Atrial fibrillation is one of the most common arrhythmias encountered in clinical practice. AF is associated with increased risk of thrombo-embolic stroke with thrombi most frequently located in the left atrial appendage (LAA). Transesophageal echocardiography (TEE) is considered the gold standard in detecting the left atrial thrombus with 97% sensitivity and 100% specificity [1]. TEE has been used in clinical practice to exclude the presence of left atrial thrombus in patients with recent onset AF that has persisted more than 48 hours or in the setting of subtherapeutic anticoagulation before cardioversion [2]. The present study aimed to determine the incidence of LAA thrombus in patients with AF and the clinical and echocardiographic parameters associated with left atrial thrombus formation.
The study was approved by the MedStar Health Research Institute Institutional Review Board and is compliant with the Health Insurance Portability and Accountability Act.
⁎ Corresponding author at: MedStar Washington Hospital Center, 110 Irving St. NW, Suite 4B1, Washington, DC 20010. Tel.: +1 202 877 2812; fax: +1 202 8772715. E-mail address: [email protected] (R. Waksman). http://dx.doi.org/10.1016/j.carrev.2014.12.009 1553-8389/© 2014 Published by Elsevier Inc.
2.1. Study population This single-center retrospective study included 600 consecutive patients with AF undergoing TEE from 2008 to 2013 for the detection of LAA thrombus before cardioversion. The patients were referred for TEE because of new onset AF more than 48 hours or with subtherapeutic international normalized ratios (goal range, 2.0–3.0) despite being on anticoagulation. Pertinent clinical features, echocardiographic parameters, laboratory parameters, and comorbidities were abstracted from the clinical records and recorded in the database.
R. Malik et al. / Cardiovascular Revascularization Medicine 16 (2015) 12–14
2.2. Transesophageal echocardiography TEE was performed using commercially available equipment (Sonos 5500 or iE33; Philips Medical Systems, Andover, MA) and interpreted by very experienced echocardiographers. Multiplane TEE was performed in a standard manner. Special attention was given to ensuring that the entire left atrium and the left atrial appendage (LAA) were recorded from the midesophageal view. LAA emptying velocity was recorded by placing the pulse-wave Doppler cursor within 1 cm of the LAA orifice. Cine loops of the left atrium and the LAA were stored. LAA thrombus was identified as independently mobile round, oval, or irregularly shaped echodensities. Dense spontaneous contrast was defined as dynamic swirling smoke, such as echo signals imaged with optimal gain settings. 2.3. Statistical analysis Statistical analysis was performed using SAS 8.2 (SAS Institute, Cary, North Carolina). Continuous variables are expressed as mean ± SD and as percentages for categorical variables. Differences between continuous variables were assessed by using Student's t-test. Categorical variables were compared using the χ 2-test or Fisher's exact test. Significance was set at p b 0.05. Multivariate logistic regression analysis was performed to identify variables with a significant correlate with LAA thrombus. To determine independent predictors of LAA thrombus, we initially performed a logistic regression model univariate analysis using all variables recorded in the categories of baseline clinical and echocardiographic characteristics. All univariate predictors of LAA thrombus with p value ≤ 0.2 were then used in a stepwise multivariate logistic regression model. P values of b0.05 were considered statistically significant for all analyses. 3. Results Left atrial thrombus is not an uncommon finding as was seen in 11.6% of our patients presenting with atrial fibrillation. The incidence of LAA thrombus based on the CHADS2 score is presented in Fig. 1. The clinical characteristics of patients with LAA thrombus compared to patients without LAA thrombus are shown in Table 1. Prior myocardial infarction 21 (29.4 %) vs. 31 (5.8), (p b 0.001); hypertension, 60 (85.7%) vs. 386 (72.8), (p 0.02); CHADS2 ≥ 2, 56 (80%) vs. 308 (58.1), (p b 0.001) prevalence was higher in patients with LAT. The echocardiographic factors in both groups with and without LAA thrombus are shown in Table 2. Patients with LAT had lower ejection fraction 38.2 ± 15.6 vs. 46.2 ± 14.5, (p b 0.001); higher LA diameter 4.98 ± 0.7 vs. 4.52 ± 0.7, (p b 0.001); dense LA SEC 44 (62.8) vs. 112 (21.1), (p b 0.001); and low LA appendage emptying velocity 21.7 ± 12.9 vs. 37.5 ± 19.4, (p b 0.001).
13
Table 1 Clinical characteristics of patients with and without left atrial appendage thrombus.
Age (years) Male gender (%) New onset AF Hypertension (%) Renal failure (%) Diabetes (%) Prior CVA (%) Prior myocardial infarction (%) CHADS2 ≥ 2(%) INR INR N 2(%)
No thrombus, N = 530
Left atrial thrombus, N = 70
p Value
65.6 ± 12.2 346 (65.2) 105 (19.8) 386 (72.8) 120 (22.6) 143 (26.9) 61 (11.5) 31 (5.8) 308 (58.1) 1.52 ± 0.63 70 (13.2)
66.3 ± 12.9 45 (64.2) 18 (25.7) 60 (85.7) 22 (31.4) 16 (22.8) 11 (15.7) 21 (29.4) 56 (80.0) 1.59 ± 0.56 9 (12.8)
0.66 0.86 0.25 0.02 0.10 0.46 0.30 b0.001 b0.001 0.38 0.93
Univariate parameters associated with LAA thrombus are presented in Table 3. After multivariate adjustment, left atrial emptying velocity was strongest associated with left atrial thrombus formation in atrial fibrillation (HR 0.89 [CI 0.83–0.96], p value b0.001). 4. Discussion 4.1. Prevalence of LAA thrombus Left atrial thrombus was found in 11.6% of our patients, and left atrial dense spontaneous contrast was found in 26%. Valerie J et al. report similar prevalence with left atrial thrombus prevalence of 9.7% and left atrial spontaneous echo contrast prevalence of 44.9%. According to this study, left ventricular ejection fraction of b 40% was the only multivariate predictor of left atrial thrombus formation [3]. The incidence of LAA thrombus is lower in patients with atrial flutter (5.4%) [4]. 4.2. Clinical predictors associated with LAA thrombus CHADS2 is a classification scheme that estimates the risk of stroke in elderly patients with AF and is most commonly used clinically to predict the risk of stroke in atrial fibrillation [5]. A CHADS score of 0 was associated with an annual risk of stroke of 1.2%, CHADS score of 1 with 2.8%, CHADS score of 2 with 3.6%, and CHADS score of 3 with 6.4%. In our study, we did not check the stroke rate, but comparably CHADS 0 was associated with prevalence of LAT of 3.2%, CHADS 1 with 6.5%, and CHADS 2 with 12.5%. Patients with a CHADS score of 3 or more had significantly higher thrombus prevalence with 18.3%. Hypertension is one the most frequent risk factors associated with thrombus formation in patients having atrial fibrillation. This was most likely because both hypertension and atrial fibrillation are very common in the elderly. Both frequently coexist [6,7]. Myocardial infarction leads to stunning of the myocardium and to stasis of the blood secondary to wall motion abnormality. This wall motion abnormality along with reduced function as a consequence of myocardial infarction leads to thrombus formation. Table 2 Echocardiographic parameters of patients with and without left atrial appendage thrombus.
Fig. 1. The incidence of left atrial appendage thrombus by CHADS2 score.
Ejection fraction (%) Mitral regurgitation ≥ moderate (%) Left atrium diameter (cm) Left atrial appendage emptying velocity (cm/sec) Left atrial dense spontaneous echo contrast (%)
No thrombus, N = 530
Left atrial thrombus, N = 70
p Value
46.2 ± 14.5 115 (21.6) 4.52 ± 0.7 37.5 ± 19.4
38.2 ± 15.6 17 (24.2) 4.98 ± 0.7 21.7 ± 12.9
b0.001 0.53 b0.001 b0.001
112 (21.1)
44 (62.8)
b0.001
14
R. Malik et al. / Cardiovascular Revascularization Medicine 16 (2015) 12–14
Table 3 Univariate and multivariate Cox analysis—correlates for left atrial appendage thrombus.
Hypertension (%) CHADS2≥ Prior myocardial infarction (%) Ejection fraction Left atrium emptying velocity Left atrium diameter Left atrium dense spontaneous echo contrast Multivariate analysis Left atrium emptying velocity
Odds ratio
Confidence interval
p Value
2.44 2.88 3.42 0.97 0.93 2.21 6.32
1.12–4.49 1.57–5.31 1.70–6.88 0.95–0.98 0.90–0.96 1.35–3.61 3.73–10.7
0.023 0.001 0.001 ≤0.001 ≤0.001 0.002 ≤0.001
0.89
0.83–0.96
b0.001
5. Limitations This study includes those limitations that are inherent to any retrospective study. One of the limitations of the study was that it was a single-center trial. In this study, we did not evaluate TEE findings in conjunction with clinical outcomes. 6. Conclusion Left atrial thrombus is not an uncommon finding in patients presenting with atrial fibrillation. It is associated clinically with prior myocardial infarction, and hypertension and echocardiographically with low ejection fraction, enlarged left atrial diameter, and reduced left atrial appendage emptying velocity.
4.3. Echocardiographic characteristics associated with LAA thrombus
References
A low CHADS score is better at stratifying people into risk groups, but it also does not take into account the echocardiographic characteristics. Left atrial appendage emptying velocity had the strongest association with the presence of thrombus in the left atrium/left atrial appendage in patients suffering from atrial fibrillation. It is a measure of the contraction power of the atrium. Lowering the emptying velocity more will be the stasis of blood and will predispose to thrombus formation and eventually stroke. Patients with left atrial dense spontaneous contrast tend to have low left atrial contraction (emptying) velocity [8]. Dense spontaneous echo contrast is known to be an independent predictor of a higher incidence of embolic events secondary to thrombus formation [9]. An enlarged left atrium on transesophageal echocardiography is significantly associated with an enlarged LAA [10]. Dilation of the LAA is a factor that contributes to LAA thrombus formation in patients with sinus rhythm and atrial fibrillation. Intravenous contrast imaging studies have shown that remove comma compared to thrombus-free patients, the LAA is significantly larger in patients with a thrombus [11,12]. In our cohort as well, increased left atrial diameter was associated with increased left atrial thrombus formation. Some studies showed that presence of severe mitral regurgitation can be preventive in LA thrombus formation. It may be that mitral regurgitation increases the turbulent flow of blood in left atrial appendage, decreasing stagnation of blood and preventing thrombus formation. In our study, we did not find that mitral regurgitation decrease (d) LAT formation.
[1] Koca V, Bozat T, Akkaya V, Sarikamis C, Turk T, Vural H, et al. Left atrial thrombus detection with multiplane transesophageal echocardiography: an echocardiographic study with surgical verification. J Heart Valve Dis 1999;8:63–6. [2] ACC/AHA/ECS 2006 guidelines for the management of patients with atrial fibrillation. J Am Coll Cardiol 2006;48:e149–246. [3] 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. [4] Alyeshmerni D, Pirmohamed A, Barac A, Smirniotopoulos J, Xue E, Goldstein S, et al. Transesophageal echocardiographic screening before atrial flutter ablation: is it necessary for patient safety? J Am Soc Echocardiogr 2013;26:1099–105. [5] Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864–70. [6] Manolis AJ, Rosei EA, Coca A, Cifkova R, Erdine SE, Kjeldsen S, et al. Hypertension and atrial fibrillation: diagnostic approach, prevention and treatment. Position paper of the Working Group ‘Hypertension Arrhythmias and Thrombosis’ of the European Society of Hypertension. J Hypertens 2012;30:239–52. [7] Nieuwlaat R, Capucci A, Camm AJ, Olsson SB, Andresen D, Davies DW, et al. Atrial fibrillation management: a prospective survey in ESC member countries: the Euro Heart Survey on Atrial Fibrillation. Eur Heart J 2005;26:2422–34. [8] Uretsky S, Shah A, Bangalore S, Rosenberg L, Sarji R, Cantales DR, et al. Assessment of left atrial appendage function with transthoracic tissue Doppler echocardiography. Eur J Echocardiogr 2009;10:363–71. [9] Bernhardt P, Schmidt H, Hammerstingl C, Lüderitz B, Omran H. 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. J Am Coll Cardiol 2005;45(11):1807–12. [10] Al-Saady NM, Obel OA, Camm AJ. Left atrial appendage: structure, function, and role in thromboembolism. Heart 1999;82:547–54. [11] Pollick C, Taylor D. Assessment of left atrial appendage function by transesophageal echocardiography. Implications for the development of thrombus. Circulation 1991; 84:223–31. [12] Kato H, Nakanishi M, Maekawa N, Ohnishi T, Yamamoto M. Evaluation of left atrial appendage stasis in patients with atrial fibrillation using transesophageal echocardiography with an intravenous albumin-contrast agent. Am J Cardiol 1996;78:365–9.
Contents lists available at ScienceDirect
Cardiovascular Revascularization Medicine
Prevalence and predictors of left atrial thrombus in patients with atrial fibrillation: is transesophageal echocardiography necessary before cardioversion? Rahul Malik a, Daniel M. Alyeshmerni b, Zuyue Wang a, Steven A. Goldstein a, Rebecca Torguson a, Joseph Lindsay a, Ron Waksman a,⁎, Itsik Ben-Dor a a b
Division of Cardiology, Washington Hospital Center, Washington, DC Division of Cardiology, University of Michigan Health System, Ann Arbor, MI
a r t i c l e
i n f o
Article history: Received 17 December 2014 Accepted 17 December 2014 Keywords: Thrombus Atrial fibrillation Left atrial thrombus
a b s t r a c t Background: Systemic embolization threatens patients with atrial fibrillation (AF). The risk is enhanced at the time of cardioversion. Transesophageal echocardiography (TEE) prior to cardioversion to screen for left atrial thrombus (LAT), a marker of high risk for embolization, is recommended for many patients with AF. Objective: To determine clinical and echocardiographic factors associated with LAT formation in AF. Methods: Data from 600 consecutive patients with AF undergoing TEE prior to cardioversion for the detection of LAT were analyzed. Clinical, laboratory, and echocardiographic parameters were abstracted from the clinical record. Results: TEE identified LAT in 70 (11.6%) and dense (LA) spontaneous echo contrast (SEC) in 156 (26%). Baseline characteristics and echocardiographic parameters of patients with or without LAT are compared. A prior myocardial infarction, 21 (29.4 %) vs. 31 (5.8), (p b 0.001); hypertension, 60 (85.7%) vs. 386 (72.8), (p 0.02); CHADS 2 ≥ 2, 56 (80%) vs. 308 (58.1%), (p b 0.001) prevalence was higher in patients with LAT. Patients with LAT had lower ejection fraction 38.2 ± 15.6 vs. 46.2 ± 14.5, (p b 0.001); higher LA diameter 4.98 ± 0.7 vs. 4.52 ± 0.7, (p b 0.001); dense LA SEC 44 (62.8) vs. 112 (21.1), (p b 0.001); and low LA appendage emptying velocity 21.7 ± 12.9 vs. 37.5 ± 19.4, (p b 0.001). Multivariate analysis was done, and it revealed that low LA emptying velocity had the strongest independent association with LAT (HR 0.89 [CI 0.83–0.96], p value b0.001. Conclusion: LAT is not an uncommon finding of AF patients prior to cardioversion. The current practice of TEE examination may be justified since neither clinical nor routine 2D echo examinations reliably identify LAT. © 2014 Published by Elsevier Inc.
1. Introduction
2. Methods
Atrial fibrillation is one of the most common arrhythmias encountered in clinical practice. AF is associated with increased risk of thrombo-embolic stroke with thrombi most frequently located in the left atrial appendage (LAA). Transesophageal echocardiography (TEE) is considered the gold standard in detecting the left atrial thrombus with 97% sensitivity and 100% specificity [1]. TEE has been used in clinical practice to exclude the presence of left atrial thrombus in patients with recent onset AF that has persisted more than 48 hours or in the setting of subtherapeutic anticoagulation before cardioversion [2]. The present study aimed to determine the incidence of LAA thrombus in patients with AF and the clinical and echocardiographic parameters associated with left atrial thrombus formation.
The study was approved by the MedStar Health Research Institute Institutional Review Board and is compliant with the Health Insurance Portability and Accountability Act.
⁎ Corresponding author at: MedStar Washington Hospital Center, 110 Irving St. NW, Suite 4B1, Washington, DC 20010. Tel.: +1 202 877 2812; fax: +1 202 8772715. E-mail address: [email protected] (R. Waksman). http://dx.doi.org/10.1016/j.carrev.2014.12.009 1553-8389/© 2014 Published by Elsevier Inc.
2.1. Study population This single-center retrospective study included 600 consecutive patients with AF undergoing TEE from 2008 to 2013 for the detection of LAA thrombus before cardioversion. The patients were referred for TEE because of new onset AF more than 48 hours or with subtherapeutic international normalized ratios (goal range, 2.0–3.0) despite being on anticoagulation. Pertinent clinical features, echocardiographic parameters, laboratory parameters, and comorbidities were abstracted from the clinical records and recorded in the database.
R. Malik et al. / Cardiovascular Revascularization Medicine 16 (2015) 12–14
2.2. Transesophageal echocardiography TEE was performed using commercially available equipment (Sonos 5500 or iE33; Philips Medical Systems, Andover, MA) and interpreted by very experienced echocardiographers. Multiplane TEE was performed in a standard manner. Special attention was given to ensuring that the entire left atrium and the left atrial appendage (LAA) were recorded from the midesophageal view. LAA emptying velocity was recorded by placing the pulse-wave Doppler cursor within 1 cm of the LAA orifice. Cine loops of the left atrium and the LAA were stored. LAA thrombus was identified as independently mobile round, oval, or irregularly shaped echodensities. Dense spontaneous contrast was defined as dynamic swirling smoke, such as echo signals imaged with optimal gain settings. 2.3. Statistical analysis Statistical analysis was performed using SAS 8.2 (SAS Institute, Cary, North Carolina). Continuous variables are expressed as mean ± SD and as percentages for categorical variables. Differences between continuous variables were assessed by using Student's t-test. Categorical variables were compared using the χ 2-test or Fisher's exact test. Significance was set at p b 0.05. Multivariate logistic regression analysis was performed to identify variables with a significant correlate with LAA thrombus. To determine independent predictors of LAA thrombus, we initially performed a logistic regression model univariate analysis using all variables recorded in the categories of baseline clinical and echocardiographic characteristics. All univariate predictors of LAA thrombus with p value ≤ 0.2 were then used in a stepwise multivariate logistic regression model. P values of b0.05 were considered statistically significant for all analyses. 3. Results Left atrial thrombus is not an uncommon finding as was seen in 11.6% of our patients presenting with atrial fibrillation. The incidence of LAA thrombus based on the CHADS2 score is presented in Fig. 1. The clinical characteristics of patients with LAA thrombus compared to patients without LAA thrombus are shown in Table 1. Prior myocardial infarction 21 (29.4 %) vs. 31 (5.8), (p b 0.001); hypertension, 60 (85.7%) vs. 386 (72.8), (p 0.02); CHADS2 ≥ 2, 56 (80%) vs. 308 (58.1), (p b 0.001) prevalence was higher in patients with LAT. The echocardiographic factors in both groups with and without LAA thrombus are shown in Table 2. Patients with LAT had lower ejection fraction 38.2 ± 15.6 vs. 46.2 ± 14.5, (p b 0.001); higher LA diameter 4.98 ± 0.7 vs. 4.52 ± 0.7, (p b 0.001); dense LA SEC 44 (62.8) vs. 112 (21.1), (p b 0.001); and low LA appendage emptying velocity 21.7 ± 12.9 vs. 37.5 ± 19.4, (p b 0.001).
13
Table 1 Clinical characteristics of patients with and without left atrial appendage thrombus.
Age (years) Male gender (%) New onset AF Hypertension (%) Renal failure (%) Diabetes (%) Prior CVA (%) Prior myocardial infarction (%) CHADS2 ≥ 2(%) INR INR N 2(%)
No thrombus, N = 530
Left atrial thrombus, N = 70
p Value
65.6 ± 12.2 346 (65.2) 105 (19.8) 386 (72.8) 120 (22.6) 143 (26.9) 61 (11.5) 31 (5.8) 308 (58.1) 1.52 ± 0.63 70 (13.2)
66.3 ± 12.9 45 (64.2) 18 (25.7) 60 (85.7) 22 (31.4) 16 (22.8) 11 (15.7) 21 (29.4) 56 (80.0) 1.59 ± 0.56 9 (12.8)
0.66 0.86 0.25 0.02 0.10 0.46 0.30 b0.001 b0.001 0.38 0.93
Univariate parameters associated with LAA thrombus are presented in Table 3. After multivariate adjustment, left atrial emptying velocity was strongest associated with left atrial thrombus formation in atrial fibrillation (HR 0.89 [CI 0.83–0.96], p value b0.001). 4. Discussion 4.1. Prevalence of LAA thrombus Left atrial thrombus was found in 11.6% of our patients, and left atrial dense spontaneous contrast was found in 26%. Valerie J et al. report similar prevalence with left atrial thrombus prevalence of 9.7% and left atrial spontaneous echo contrast prevalence of 44.9%. According to this study, left ventricular ejection fraction of b 40% was the only multivariate predictor of left atrial thrombus formation [3]. The incidence of LAA thrombus is lower in patients with atrial flutter (5.4%) [4]. 4.2. Clinical predictors associated with LAA thrombus CHADS2 is a classification scheme that estimates the risk of stroke in elderly patients with AF and is most commonly used clinically to predict the risk of stroke in atrial fibrillation [5]. A CHADS score of 0 was associated with an annual risk of stroke of 1.2%, CHADS score of 1 with 2.8%, CHADS score of 2 with 3.6%, and CHADS score of 3 with 6.4%. In our study, we did not check the stroke rate, but comparably CHADS 0 was associated with prevalence of LAT of 3.2%, CHADS 1 with 6.5%, and CHADS 2 with 12.5%. Patients with a CHADS score of 3 or more had significantly higher thrombus prevalence with 18.3%. Hypertension is one the most frequent risk factors associated with thrombus formation in patients having atrial fibrillation. This was most likely because both hypertension and atrial fibrillation are very common in the elderly. Both frequently coexist [6,7]. Myocardial infarction leads to stunning of the myocardium and to stasis of the blood secondary to wall motion abnormality. This wall motion abnormality along with reduced function as a consequence of myocardial infarction leads to thrombus formation. Table 2 Echocardiographic parameters of patients with and without left atrial appendage thrombus.
Fig. 1. The incidence of left atrial appendage thrombus by CHADS2 score.
Ejection fraction (%) Mitral regurgitation ≥ moderate (%) Left atrium diameter (cm) Left atrial appendage emptying velocity (cm/sec) Left atrial dense spontaneous echo contrast (%)
No thrombus, N = 530
Left atrial thrombus, N = 70
p Value
46.2 ± 14.5 115 (21.6) 4.52 ± 0.7 37.5 ± 19.4
38.2 ± 15.6 17 (24.2) 4.98 ± 0.7 21.7 ± 12.9
b0.001 0.53 b0.001 b0.001
112 (21.1)
44 (62.8)
b0.001
14
R. Malik et al. / Cardiovascular Revascularization Medicine 16 (2015) 12–14
Table 3 Univariate and multivariate Cox analysis—correlates for left atrial appendage thrombus.
Hypertension (%) CHADS2≥ Prior myocardial infarction (%) Ejection fraction Left atrium emptying velocity Left atrium diameter Left atrium dense spontaneous echo contrast Multivariate analysis Left atrium emptying velocity
Odds ratio
Confidence interval
p Value
2.44 2.88 3.42 0.97 0.93 2.21 6.32
1.12–4.49 1.57–5.31 1.70–6.88 0.95–0.98 0.90–0.96 1.35–3.61 3.73–10.7
0.023 0.001 0.001 ≤0.001 ≤0.001 0.002 ≤0.001
0.89
0.83–0.96
b0.001
5. Limitations This study includes those limitations that are inherent to any retrospective study. One of the limitations of the study was that it was a single-center trial. In this study, we did not evaluate TEE findings in conjunction with clinical outcomes. 6. Conclusion Left atrial thrombus is not an uncommon finding in patients presenting with atrial fibrillation. It is associated clinically with prior myocardial infarction, and hypertension and echocardiographically with low ejection fraction, enlarged left atrial diameter, and reduced left atrial appendage emptying velocity.
4.3. Echocardiographic characteristics associated with LAA thrombus
References
A low CHADS score is better at stratifying people into risk groups, but it also does not take into account the echocardiographic characteristics. Left atrial appendage emptying velocity had the strongest association with the presence of thrombus in the left atrium/left atrial appendage in patients suffering from atrial fibrillation. It is a measure of the contraction power of the atrium. Lowering the emptying velocity more will be the stasis of blood and will predispose to thrombus formation and eventually stroke. Patients with left atrial dense spontaneous contrast tend to have low left atrial contraction (emptying) velocity [8]. Dense spontaneous echo contrast is known to be an independent predictor of a higher incidence of embolic events secondary to thrombus formation [9]. An enlarged left atrium on transesophageal echocardiography is significantly associated with an enlarged LAA [10]. Dilation of the LAA is a factor that contributes to LAA thrombus formation in patients with sinus rhythm and atrial fibrillation. Intravenous contrast imaging studies have shown that remove comma compared to thrombus-free patients, the LAA is significantly larger in patients with a thrombus [11,12]. In our cohort as well, increased left atrial diameter was associated with increased left atrial thrombus formation. Some studies showed that presence of severe mitral regurgitation can be preventive in LA thrombus formation. It may be that mitral regurgitation increases the turbulent flow of blood in left atrial appendage, decreasing stagnation of blood and preventing thrombus formation. In our study, we did not find that mitral regurgitation decrease (d) LAT formation.
[1] Koca V, Bozat T, Akkaya V, Sarikamis C, Turk T, Vural H, et al. Left atrial thrombus detection with multiplane transesophageal echocardiography: an echocardiographic study with surgical verification. J Heart Valve Dis 1999;8:63–6. [2] ACC/AHA/ECS 2006 guidelines for the management of patients with atrial fibrillation. J Am Coll Cardiol 2006;48:e149–246. [3] 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. [4] Alyeshmerni D, Pirmohamed A, Barac A, Smirniotopoulos J, Xue E, Goldstein S, et al. Transesophageal echocardiographic screening before atrial flutter ablation: is it necessary for patient safety? J Am Soc Echocardiogr 2013;26:1099–105. [5] Gage BF, Waterman AD, Shannon W, Boechler M, Rich MW, Radford MJ. Validation of clinical classification schemes for predicting stroke: results from the National Registry of Atrial Fibrillation. JAMA 2001;285:2864–70. [6] Manolis AJ, Rosei EA, Coca A, Cifkova R, Erdine SE, Kjeldsen S, et al. Hypertension and atrial fibrillation: diagnostic approach, prevention and treatment. Position paper of the Working Group ‘Hypertension Arrhythmias and Thrombosis’ of the European Society of Hypertension. J Hypertens 2012;30:239–52. [7] Nieuwlaat R, Capucci A, Camm AJ, Olsson SB, Andresen D, Davies DW, et al. Atrial fibrillation management: a prospective survey in ESC member countries: the Euro Heart Survey on Atrial Fibrillation. Eur Heart J 2005;26:2422–34. [8] Uretsky S, Shah A, Bangalore S, Rosenberg L, Sarji R, Cantales DR, et al. Assessment of left atrial appendage function with transthoracic tissue Doppler echocardiography. Eur J Echocardiogr 2009;10:363–71. [9] Bernhardt P, Schmidt H, Hammerstingl C, Lüderitz B, Omran H. 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. J Am Coll Cardiol 2005;45(11):1807–12. [10] Al-Saady NM, Obel OA, Camm AJ. Left atrial appendage: structure, function, and role in thromboembolism. Heart 1999;82:547–54. [11] Pollick C, Taylor D. Assessment of left atrial appendage function by transesophageal echocardiography. Implications for the development of thrombus. Circulation 1991; 84:223–31. [12] Kato H, Nakanishi M, Maekawa N, Ohnishi T, Yamamoto M. Evaluation of left atrial appendage stasis in patients with atrial fibrillation using transesophageal echocardiography with an intravenous albumin-contrast agent. Am J Cardiol 1996;78:365–9.
