Abstract 14612: Does the Open Smooth Antrum of the Left Atrial Appendage Serve as a Nidus for Thrombus Formation in Patients With Atrial Fibrillation and Surgical Appendage Clip i n situ ?

Introduction: Atrial fibrillation (AF) is a significant risk factor for embolic stroke originating from the left atrial appendage (LAA). LAA occlusion is recommended in patients that are not amenable to anticoagulation therapy because of elevated CHADS 2 or CHA 2 DS 2 -VASC score. We assessed the risk of stroke off anticoagulants in AF patients following LAA occlusion with appendage clip device. Methods: One hundred eighty-five AF patients (age 66±13, males 69%, CHADS 2 2.6± 0.8, CHA 2 DS 2 -VASC 3.5± 1.2) that received surgical left atrial appendage occlusion device (clip) were included in this analysis. Transesophageal echocardiogram (TEE) was performed at the end of the procedure to evaluate successful closure of the antrum of the LAA and was repeated at 1 and 6-month post-procedure. Patients remained on oral anticoagulants for 1-month post-procedure after which it was discontinued. All patients were monitored for thrombo-embolic complications for at least 1 year by TEE, clinic visits at 3-month intervals and phone calls by our research staffs. Result: The follow-up TEE revealed the LAA clip to be stable without any secondary displacement. No LAA thrombus was detected. Interestingly, in 177 (95.6%) patients, TEE revealed the proximal part of the smooth antrum of the LAA neck below the clip, to be still open. At the end of the 24±3 months of follow-up, no stroke or transient ischemic attack (TIA) or other neurological events were observed in the study population (0 of 155, 0%). Conclusions: In patients with AF in whom oral anticoagulation is deemed unsuitable because of high CHADS 2 or CHA 2 DS 2 -VASC score, left atrial appendage closure with surgical clip device seems to be safe and effective in preventing stroke. It is relatively common to find incomplete obliteration of the LAA with the surgical clip with the proximal portion of the smooth antrum still remaining open as the clip is typically seen to be placed higher up in the LAA neck. However, presence of the open smooth-antrum did not increase the risk of stroke even after discontinuation of anticoagulants.