Reviwer : Dr. Cem Çöteli

Name of the Study : Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke (LAAOS III Trial)

Published in Congress : ACC 2021

Link : https://www.nejm.org/doi/full/10.1056/NEJMoa2101897

Background :
Atrial fibrillation is a common disorder in the elderly population. Cardioembolic events are responsible for a quarter of ischemic stroke and the left atrial appendage is generally the origin of the thrombus formation in these events. Even though oral anticoagulant drugs are effective for thromboembolic prevention, they have some disadvantages. Left atrial appendage occlusion could be performed concomitantly in patients who will undergo cardiac surgery.

Objective :
The authors hypothesized that concomitant LAA occlusion could reduce embolic risk in patients who will undergo cardiac surgery, and have atrial fibrillation, with accompany of anticoagulant therapy. It is aimed to show if LAA occlusion procedure present benefit of embolic prevention additional to the anticoagulant therapy.

Method :
The LAAOS III trial is a multicenter, prospective, randomized controlled study. Patients who are older than 18 years have atrial fibrillation and more than 2  point CHA2DS2-VASc scores, are candidates for cardiac surgery which will undergo cardiopulmonary bypass surgery were enrolled. The patients who will undergo off-pump surgery, mechanical heart valve implantation, heart transplantation, complex congenital heart surgery, and LVAD implantation were excluded. The patients who have history of surgery which pericardium had been opened, and LAA closure device were also not enrolled. The patients were randomized 1:1 and grouped as LAA occluded and non-LAA occluded. Different LAA occlusion techniques were performed (Amputation or with closure devices) . Participants were followed up by telephone or in-person (primarily by telephone) at 30 days and then 6 months. The primary outcome was ischemic stroke (Included TIA diagnosed with imaging) or non-cerebral systemic emboly.

Results :
The LAA was occluded in 2379 patients and not occluded in 2391patients. The mean age was 71 years, and the mean CHA2DS2-VASc score was 4.2. The mean follow-up duration was 3.8 years. At the 3 years follow-up, 76.8% of the patients were still under anticoagulant therapy. In the occlusion group, stroke or systemic emboli were observed in 114 patients (4.8%). In the non-occlusion group, the primary outcomes were observed 168 patients (7%).  (Hazard ratio, 0.67; 95% confidence interval, 0.53 to 0.85; P = 0.001). Perioperative bleeding, heart failure, and death were not different between the groups.

Conclusion :
In patients who had undergone LAA occlusion during cardiac surgery faced ischemic stroke or systemic emboli lower than the patients who had not undergone LAA occlusion.

Interpretation :
Both percutaneous and surgical LAA occlusion is one of the controversial topics of cardiac interventions. Insight of recent guidelines, LAA occlusion is performed in patients who are intolerant or have an absolute contraindication to anticoagulants. In this study, the authors investigated the significance of LAA occlusion in patients under anticoagulant therapy.  When the LAA occlusion procedure is being debated in patients intolerant to anticoagulants, the LAAOS III trial moved this controversy to another level.