Congenital Absence of the Left Atrial Appendage and Possible Effects on Thrombosis: A Case Report.

The left atrial appendage (LAA) is a common site for thrombus formation in atrial fibrillation (AF) and often the focus of imaging prior to cardioversion. We present a rare case of a 64-year-old male undergoing routine transesophageal echocardiography (TEE) prior to electrical cardioversion, during which the LAA was not visualized. Further evaluation confirmed congenital absence of the LAA - a seldom-reported finding with uncertain implications for stroke risk and anticoagulation management. This report adds to the limited literature on this anomaly and underscores the importance of a systematic approach when faced with unexpected imaging findings. Although the absence of the LAA might theoretically reduce thromboembolic risk, current evidence is insufficient to alter management, and standard anticoagulation guidelines for AF should still be followed.