The elephant trunk: a rare morphology of the left atrial appendage-a case report.

Background: Patients with atrial fibrillation (AF) are at increased risk for thromboembolic events including stroke. The primary source for thromboembolism in these patients is thrombus formation in the left atrial appendage (LAA). Depending on the individual thromboembolic risk, long-term anticoagulation is recommended. In certain patients, however, long-term anticoagulation is contraindicated, and interventional closure of the LAA (LAAC) represents an alternative approach to lower the thromboembolic risk and avoid oral anticoagulation. Case summary: An 83-year-old male underwent LAAC at our centre in November 2022. Prior to the procedure, a thrombus in the left atrium (LA) or LAA was excluded by transoesophageal echocardiography (TOE), and the anatomy of the LAA was assessed as eligible for LAAC with no evidence of anatomical irregularities. After contrast medium injection, angiography revealed an atypical anatomic variant of the LAA with a substantially long, elephant trunk-like course. Discussion: We present a previously not described unique anatomic variant of the LAA: the elephant trunk morphology. Left atrial appendage anatomy is very heterogeneous, and detailed knowledge of LAA morphology is important for endovascular LAA procedures as well as for predicting the risk of thromboembolic events. Despite thorough pre-procedural imaging, anatomic variants may remain obscured.