Cardiac computed tomography and magnetic resonance imaging vs. transoesophageal echocardiography for diagnosing left atrial appendage thrombi

AIMS: Transoesophageal echocardiography (TOE) is the gold standard for identification of left atrial appendage (LAA) thrombi. However, TOE is semi-invasive and cannot be performed in certain patients. Left atrial appendage thrombi can also be identified by cardiac computed tomography (CCT) and cardiac magnetic resonance imaging (CMR); however, the diagnostic performance of these techniques vs. TOE is unclear. METHODS AND RESULTS: We performed a systematic review and meta-analysis of 22 CCT and 4 CMR studies comparing diagnostic performance to TOE for identification of LAA thrombi. Meta-regression was performed to determine whether expected sensitivity and specificity differed between early and delayed image acquisition protocols for CCT vs. TOE and between CCT and CMR. Cardiac computed tomography demonstrated sensitivity and specificity of 0.99 [confidence interval (CI 0.93-1.00)] and 0.94 (CI 0.90-0.97) respectively vs. TOE. A subgroup analysis comparing early vs. delayed protocol CCT imaging was performed showing no significant differences in sensitivity (P-value = 0.17) however improved specificity of the delayed imaging protocols (P-value = 0.04). Cardiac magnetic resonance imaging demonstrated sensitivity and specificity of 0.80 (CI 0.63-0.91) and 0.98 (CI 0.97-0.99), respectively when compared to TOE. There was no significant difference in sensitivity or specificity between CMR and CCT (P-values 0.996 and 0.484, respectively). CONCLUSION: Cardiac computed tomography and CMR had good to excellent sensitivity and specificity vs. TOE. Further, there was no significant difference in the sensitivity and specificity of CCT vs. CMR, suggesting that both modalities can be considered reasonable alternatives to TOE in the identification of LAA thrombi. Cardiac magnetic resonance imaging may be especially beneficial when TOE and CCT cannot be performed.