Cardiac imaging for assessment of left atrial appendage stasis and thrombosis

Atrial fibrillation (AF) is the most-common arrhythmia in the elderly population (age >65 years). The left atrial appendage (LAA) is the main location of thrombus formation, predominantly in patients with nonvalvular AF. This Review is focused on the pathophysiology, assessment, and clinical implications of stasis (or spontaneous echocardiographic contrast; SEC) and thrombus formation in the LAA. The gold-standard modality for assessment of SEC and thrombus in the LAA is echocardiography, particularly transoesophageal echocardiography (TEE). Cardiac CT (CCT) is an accurate, noninvasive alternative to TEE for the detection of LAA thrombi, distinctly when delayed-imaging acquisition protocols are used. Prospective studies to validate the use of cardiac MRI (CMR) for this purpose are needed, and will avoid the need for radiation and iodinated contrast. CCT or CMR could potentially be implemented to rule out LAA thrombus, avoiding unnecessary preprocedural TEE. Cardiac imaging is also of primary importance in the setting of LAA closure devices and electrophysiological studies. New trials are needed to compare the various imaging modalities, with surgicopathological findings as a reference standard.