Assessment and Management of the Left Atrial Appendage Thrombus in Patients With Nonvalvular Atrial Fibrillation

Background: Intracardiac thrombi arising in the left atrial appendage (LAA) are the principal cause of stroke in nonvalvular atrial fibrillation (AF). Predicting the presence of LAA thrombi is of vital importance in stratifying patients that would need further LAA imaging prior to cardioversion or AF ablation. Methods: We comprehensively searched PubMed from its inception to November 2017 for randomized controlled trials, cohort and case control studies, as well as for case series on LAA thrombi risk factors, imaging, prevention, and anticoagulation management in atrial fibrillation. Results: A systematic review of the literature identified 106 articles that investigated the presence of LAA thrombi in AF patients. We classified the articles according to topic and reported on: (1) risk factors; (2) diagnostic imaging modalities; (3) prevention strategies before cardioversion; (4) prevention strategies before AF ablation; and (5) management of detected LAA thrombi. Conclusions: Integration of clinical, biomarker, and imaging risk factors can improve overall prediction for the presence of LAA thrombi, translating into improved patient selection for imaging. The gold standard for the diagnosis of LAA thrombi remains transesophageal echocardiography, although intracardiac ultrasound, cardiac computed tomography, and cardiovascular magnetic imaging are promising alternative modalities. When LAA thrombi are discovered, the treatment regimen remains variable, although direct oral anticoagulants might have efficacy similar to vitamin K antagonists. Future trials will help further elucidate direct oral anticoagulant use for the treatment of LAA thrombi.