Techniques to improve left atrial appendage imaging

The clinical importance of the left atrial appendage (LAA) is increasingly recognized. The assessment of the unique anatomy and function of the LAA is especially important in the setting of atrial fibrillation (AF). AF is the most commonly occurring cardiac arrhythmia, and the association of LAA thrombi and AF has been well established. Transesophageal echocardiography (TEE) is a widely available imaging tool to exclude the potential presence of LAA thrombus prior to cardioversion in patients with AF. Commercially available products containing microbubbles to enhance ultrasound images, termed "ultrasound contrast agents" (UCA) are indicated for use with transthoracic echocardiography to improve cardiac structure and function assessment, but can also be used with TEE as an adjunctive tool to assess the LAA. Integrative multimodality imaging techniques can be used in evaluation of the LAA as indicated in various clinical scenarios including: stroke risk assessment, decision-making prior to cardioversion in AF, placement and assessment percutaneous transcatheter LAA occlusion procedures, and assessment of results of procedural or surgical exclusion of LAA. In this article, various imaging techniques that are available for non-invasive visualization of the LAA will be reviewed along with the clinical importance of assessment of LAA anatomy and function.