Detection of Left Atrial Appendage Thrombus by Cardiac Computed Tomography in Patients With Atrial Fibrillation

Abstract

Background-Transesophageal echocardiogram (TEE) is considered the gold standard modality in detecting left atrial/ LA appendage (LA/LAA) thrombi. However, this is a semi-invasive procedure with rare but potential life-threatening complications. Cardiac computed tomography has been proposed as an alternative method. The purpose of this metaanalysis was to evaluate the diagnostic accuracy of cardiac computed tomography assessing LA/LAA thrombi in comparison with TEE. Methods and Results-A systematic review of Medline, Cochrane, and Embase to look for clinical trials assessing detection of LA/LAA thrombi by cardiac computed tomography when compared with TEE in patients with a history of atrial fibrillation before electric cardioversion/pulmonary vein isolation or after cardioembolic cerebrovascular accident was performed using standard approach and bivariate analysis. Nineteen studies with 2955 patients (men, 71%; mean age, 61±4 years) fulfilled the inclusion criteria. Most studies (85%, 16 studies) used 64-slide multidetector computed tomography and 15 studies (79%) were electrocardiographic-gated. The incidence of LA/LAA thrombi was 8.9% (SD, ±7). The mean sensitivity and specificity were 96% and 92%, whereas the positive predictive value and negative predictive value were 41% and 99%, respectively. The diagnostic accuracy was 94%. In a subanalysis of studies in which delayed imaging was performed, the diagnostic accuracy significantly improved to a mean weighted sensitivity and specificity of 100% and 99%, respectively, whereas the positive predictive value and negative predictive value increased to 92% and 100%, respectively. The accuracy for this technique was 99%. Conclusions-Cardiac computed tomography, particularly when delayed imaging is performed, is a reliable alternative to TEE for the detection of LA/LAA thrombi/clot, avoiding the discomfort and risks associated with TEE.

Technological Improvements in Cardiac Thrombus Diagnosis

“…A recent meta-analysis demonstrated that the overall high accuracy of cardiac CT, compared with TEE, can be used to detect LA or LAA thrombus in patients with AF. The investigators included 19 studies with a total of 2955 patients and found the weighted mean sensitivity and specificity to be 96% (95% CI: 92-100%) and 92% (95% CI: 91-93%), whereas the PPV and NPV were 41% (95% CI: 37-44%) and 99% (95% CI: 99-100%), respectively [52]. This is because a pseudo-filling defect, such as flow stasis, can also cause an apparent filling defect on CT images, thereby mimicking a thrombus.…”

Role of Imaging in Left Atrial Appendage Occlusion

“…Studies with mutlidetector CT have reported good sensitivity and specificity for CCTA for LAA thrombus detection [46,47]. Recent meta-analysis demonstrated that CT shows a good diagnostic accuracy in detecting LA/ LAA thrombus with high sensitivity and specificity [48,49]. This technique has a high negative predictive value for excluding LAA thrombus.…”

“…Adaptation to CCTA protocols may improve LAA thrombus detection: delayed imaging (2-phase scan with delayed image acquisition at least 30 seconds after contrast bolus), dual-enhanced scan (single scan after 2-bolus contrast), dual-energy source and prone position [50,51]. When delayed imaging was performed, the diagnostic accuracy significantly improved across different studies [49]. Hence, CCTA, particularly when delayed imaging is performed, may be a reliable alternative for the detection of LA or LAA thrombi.…”

Tomografía computarizada cardiaca: Nuevas aplicaciones de una técnica en evolución

“…Si bien el ecocardiograma transesofágico es considerado como la regla de oro para la evaluación de la orejuela izquierda y la detección de trombos, se trata de un procedimiento semiinvasivo, en ocasiones mal tolerado y con potenciales complicaciones. Estudios recientes con TC multicorte han demostrado que se trata de una técnica útil, rápida y precisa en la detección de trombos, convirtiéndose en una alternativa válida al ecocardiograma transesofágico 17 . Al mismo tiempo, permite una valoración rápida y completa de la anatomía y dimensiones de la orejuela izquierda previa al cierre con dispositivos, así como un control de su posicionamiento tras el implante 18 (fig.…”