Left atrial appendage thrombus outside of a 'successful' ligation

A 79-year-old woman with severe aortic stenosis underwent aortic valve replacement surgery, and had ligation of the left atrial appendage (LAA) using an epicardial approach. On a post-operative echocardiographic evaluation, the distal portion of the LAA was excluded, leaving no communication with the left atrium. The proximal portion of the LAA, however, was in continuity with the circulation and a large thrombus was present within it. While previous reports of incomplete LAA ligation have involved disruption of the suture line, this present report describes a case of incomplete ligation due to persistence of the proximal portion of the appendage. Thus, thrombus formation occurred despite a 'successful' epicardial exclusion of the distal LAA.