Giant Left Atrial Appendage Aneurysm in a 6-Year-Old Girl with a Prothrombotic Genetic Predisposition: A Case Report and Literature Review

<b>Background:</b> The term 'left atrial appendage aneurysm' (LAAA) has been recognized since 1962, when it was first described. It is an exceedingly rare pathology that can affect both adults and children. Often asymptomatic, it may be discovered incidentally. The anomaly consists of an exaggerated dilation of the primitive portion of the left atrium, resulting from pectinate muscle dysplasia or as a consequence of an obstructive lesion between the left atrium and the mitral valve. Surgical intervention represents a reliable strategy for preventing catastrophic complications such as stroke, thromboembolism, and rupture. This is a very rare condition, which is why we aimed to present a case report along with a review of the literature. <b>Case presentation</b>: We report the case of a 6-year-old asymptomatic girl in whom a giant left atrial appendage aneurysm was incidentally detected during a routine transthoracic echocardiogram, associated with a small atrial septal defect and a prothrombotic genetic profile. The aneurysm was successfully excised, and the atrial septal defect was closed. The postoperative course was uneventful, and the patient was discharged home on the 8th postoperative day. <b>Conclusions</b>: Left atrial appendage aneurysm is rare in children and often asymptomatic, yet it may be life-threatening due to stroke or thromboembolism. Fetal echocardiography may be considered in selected high-risk pregnancies, and routine postnatal assessment is advised, with surgical intervention recommended particularly for patients with risk factors for thrombus formation in the left atrium or its appendage.