The risk of thromboembolism was reduced by 40 percent in AFib patients who underwent left atrial appendage occlusion (LAAO) as an add-on during cardiac surgery, according to an observational study presented March 19 at ACC.17 in Washington, DC.

Researchers performed inverse probability weighted analyses of 10,524 Medicare-linked patients from The Society of Thoracic Surgeons Adult Cardiac Surgery Database, a nationally-representative data set that includes 90 percent of cardiac surgery centers in the U.S. They extracted data for Medicare patients with AFib who underwent coronary artery bypass grafting, aortic valve surgery or mitral valve surgery in 2011 or 2012. The median age of patients was 76; 39 percent were women.

The primary endpoint was one-year readmission for thromboembolism, defined by claims data. About 37 percent of patients underwent LAAO during surgery. Of these, 1.6 percent were hospitalized for thromboembolism within 12 months, significantly fewer than the 2.5 percent of patients experiencing thromboembolism who did not undergo LAAO, indicating a 40 percent decrease in risk over 12 months.

In addition, LAAO was associated with a 15 percent reduction in all-cause mortality and a 21 percent reduction in a composite of thromboembolism, hemorrhagic stroke and death. There was no significant difference in the rate of hemorrhagic stroke.

"Intuitively, surgical left atrial appendage occlusion should work; however, there have been concerns that incomplete occlusion actually could lead to increased risk for thromboembolism because it could result in small communications between the appendage and the left atrium," said Daniel J. Friedman, MD, FACC, lead author of the study. "The fact that we saw such a dramatic association between the procedure and a reduction in thromboembolism was reassuring that, at least in a more contemporary cohort of patients, LAAO is able to be done in a much more effective way than initial reports had suggested."

Further analysis of the data showed that patients who were not taking anticoagulants at discharge experienced the greatest reduction in thromboembolism after LAAO. There was no difference in thromboembolism rates for patients who were taking anticoagulants at discharge. Additional research is needed to establish whether or not LAAO is effective enough to allow patients to safely stop taking anticoagulants.

Friedman also noted that although the study was not a randomized trial, "it does demonstrate strong support for the benefits of closing the left atrial appendage at the time of cardiac surgery in patients with atrial fibrillation."

Keywords: ACC17, ACC Annual Scientific Session, Heart Valve Diseases, Arrhythmias, Cardiac, Atrial Appendage, Atrial Fibrillation, Cardiac Surgical Procedures, Catheter Ablation, Intracranial Hemorrhages, Medicare, Patient Readmission, Stroke, Thromboembolism

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