Methods
Transthoracic Echocardiographic Predictors of Left Atrial Appendage Thrombus

https://doi.org/10.1016/j.amjcard.2005.08.065Get rights and content

Transesophageal echocardiography (TEE) is commonly performed to detect the presence of a left atrial appendage (LAA) thrombus in the setting of an embolic event or before an anticipated electrical cardioversion for atrial fibrillation. The predictive value of transthoracic echocardiographic (TTE) findings in these patients has not been well defined. This study evaluated whether TTE findings can predict LAA thrombi using TEE as the gold standard for the identification of LAA thrombi. From November 1995 to March 2003, 10,753 patients underwent TEE to exclude LAA thrombi after embolic events or before cardioversion. Of these, 3,768 patients had complete TTE examinations performed <2 weeks before undergoing TEE. Demographics, TTE, and cardiac rhythm variables were analyzed using univariate and multivariate logistic regression to identify predictors of LAA thrombi diagnosed on subsequent TEE. LAA thrombi were identified by TEE in 199 patients (5.3%). Several TTE variables predicted LAA thrombi by TEE, including mitral stenosis, atrial fibrillation, tricuspid regurgitation, valvular prosthesis, left ventricular dysfunction, and right ventricular dysfunction. Mitral regurgitation was associated with a reduced risk for LAA thrombi (odds ratio 0.61, p = 0.003). A structurally normal heart in sinus rhythm (n = 247, 6.9%) had a 100% negative predictive value for LAA thrombi. In conclusion, several TTE variables were found to be predictive of LAA thrombi. The likelihood of LAA thrombi being found on TEE was infinitely small in the absence of these variables and the presence of sinus rhythm.

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Methods

This retrospective study consisted of patients who underwent TEE at the Cleveland Clinic Foundation from November 1995 to March 2003 to exclude LAA thrombi after embolic events or before cardioversion for atrial fibrillation or atrial flutter. Examination of the database revealed 10,753 patients who underwent TEE during this time period for the stated indications. Inclusion in the study also required a TTE examination <2 weeks before TEE as well as being ≥18 years of age. Although 10,753

Results

TEE identified 199 LAA thrombi (5.3%) in the 3,768 patients who underwent TEE to evaluate for potential sources of embolism before cardioversion. Baseline clinical and echocardiographic characteristics categorized according to the presence of LAA thrombus are listed in Table 1.

Cardiac chamber size and function were predictive of LAA thrombi. Approximately 59.2% of patients with LAA thrombi had LV dysfunction, compared with 34.8% of patients without LAA thrombi (p <0.0001). Fifty-two percent of

Discussion

This study of patients presenting for TEE after embolic events or before planned cardioversion for atrial fibrillation or atrial flutter attempted to define a patient population with a low risk for LAA thrombus on the basis of TTE findings. The study also aimed to determine whether certain TTE characteristics could be used to predict the presence of LAA thrombi as identified by TEE. The population of patients found to be at the lowest risk for LAA thrombi were those with structurally normal

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    LAAT was present in 199. No LAAT occurred in the 247 patients in sinus rhythm with a structurally normal heart on TTE defined by ejection fraction > 50%, absence of left ventricular hypertrophy, absence of right ventricular (RV) hypertrophy or dysfunction, left atrial diameter < 4.0 cm, absence of aortic valve stenotic or regurgitant lesions, ≤ 1 + mitral regurgitation, absence of mitral stenosis, ≤ 1 + tricuspid regurgitation, absence of tricuspid stenosis, ≤ 1 + pulmonary regurgitation, absence of pulmonary stenosis, absence of a ventricular septal defect or an atrial septal defect, and absence of a prosthetic valve (Ellis et al., 2006). However, Mugge et al. reported that 7 of 75 LAAT detected by TEE in a cohort of 2000 patients referred for a variety of clinical reasons occurred in patients with sinus rhythm “without morphological abnormalities additional to” LAAT (Mugge et al., 1990).

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