Summary
Transoesophageal echocardiogram is the gold-standard for the detection of thrombi in the LAA . This is a semi-invasive technique that despite a very low incidence of complications carries risks over transthoracic imaging . While transthoracic echocardiography is now a highly versatile technique that provides solid structural and functional information about the atria.
Many clinical reports have indicated that left atrial (LA) mechanical remodeling is associated with thrombus formation in the LAA. The presence of spontaneous echocardiographic contrast or reduced LAA peak flow velocity, as measured by transoesophageal echocardiography (TEE), was reported to be useful for detecting LAA dysfunction, which causes thrombus formation in the LAA.
TDI and Speckle tracking are imaging techniques that provides accurate information regarding left atrial deformation and motion. Echocardiographic parameters assessing structure, like left atrial size, are known to impact on the presence of left atrial stasis (thrombi or sludge, dense spontaneous echocardiographic contrast and low flow velocities in the LAA).
250 patients indicated for TEE were enrolled in this study, They were investigated with TTE before TEE examination and divided into 2 groups according to TEE .
♦ Group I: included 110 patients with LAA thrombus or SEC .
♦ Group II: included 140 patients without LAA thrombus or SEC .
The demographic data &risk factors including hypertension, diabetes& smoking were similar in both groups.
There were no significant difference as regard demographic data and risk factors between the 2 groups .
Group 1 patients who had LAA thrombus or SEC tend to have larger LA diameter while they tend to have lower left atrial function and lower LAA emptying velocity .
Mean strain and stain rate measured by TDI & 2D speckle tracking correlate well with LAA function and LAA emptying velocity. The correlation between mean strain and strain rate measured by TDI or 2D speckle tracking and LAA function and LAA emptying velocity measured by TEE is valid in both sinus rhythm and atrial fibrillation rhythm.
Patients with valvular heart disease found to have significant correlation between mean strain and strain rate and LAA function &LAA emptying velocity.
ROC curve was used to test the diagnostic value (overall accuracy) of 2D global strain and 2D global strain rate measured by speckle tracking in predicting LAA mass or shadow. 2D global strain cutoff value of < 31 was shown to have the best diagnostic accuracy (sensitivity = 88.2% & specificity = 77.9 %) in predicting LAA mass or shadow [AUC 0.833 95% CIs (0.779 - 0.887), P < 0.001]. 2D global strain rate cutoff value of < 1.16 was shown to have the best diagnostic accuracy (sensitivity = 87.3% & specificity = 75.7%) in predicting LAA mass or shadow [AUC 0.811, 95% CIs (0.754 - 0.867), P < 0.001] .
TDI mean strain cutoff value of < 23.42 was shown to have the best diagnostic accuracy (sensitivity = 85.5% & specificity = 82.1%) in predicting LAA mass or shadow [AUC 0.839 95% CIs (0.785 - 0.892), P < 0.001]. TDI mean strain rate cutoff value of < 1.45 was shown to have the best diagnostic accuracy (sensitivity = 87.3% & specificity = 78.6%) in predicting LAA mass or shadow [AUC 0.819, 95% CIs (0.763 - 0.875), P < 0.001].
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