ACC.17: LAAO at the time of cardiac surgery may reduce thromboembolism, mortality

Older adults with atrial fibrillation who underwent left atrial appendage occlusion (LAAO) at the time of cardiac surgery had an approximately 40 percent reduction in thromboembolism and a 15 percent reduction in all-cause mortality, according to a database analysis.

Lead researcher Daniel J. Friedman, MD, of the Duke Clinical Research Institute, presented results of the study in a late-breaking clinical trial session at the ACC scientific session on March 19 in Washington, D.C.

“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,” Friedman said in a news release. “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, left atrial appendage occlusion is able to be done in a much more effective way than initial reports had suggested may be the case.”

The researchers analyzed the Society of Thoracic Surgeons (STS) adult cardiac surgery database for 2011 to 2012, which included information on more than 1,000 institutions and more than 90 percent of cardiothoracic surgical programs in the U.S. They then linked the database to Medicare claims.

The 10,524 patients in the study were at least 65 years old, had atrial fibrillation or atrial flutter, underwent their first cardiac surgery, had Medicare coverage and had at least six months of follow-up after discharge. The median age was 76 years old, and 39 percent of the patients were females.

Of the patients, 37 percent underwent LAAO at the time of cardiac surgery. In addition, 35 percent underwent isolated CABG, 35 percent had an aortic procedure with or without CABG and 30 percent had a mitral procedure with or without CABG.

The researchers found that LAAO was associated with non-paroxysmal atrial fibrillation, higher ejection fraction, mitral operations and surgical ablation, academic medical centers, lower STS Predicted Risk of Mortality scores and fewer stroke risk factors such as diabetes, hypertension and a history of stroke.

Within 12 months, 1.6 percent of patients in the LAAO group and 2.5 percent of patients in the non-LAAO group were hospitalized for thromboembolism, which translated to a statistically significant 40 percent risk reduction.

The 12-month all-cause mortality rates were 7 percent in the LAAO group and 10.8 percent in the non-LAAO group, which represented a 15 percent reduction. The 12-month hemorrhagic stroke rates were 0.2 percent and 0.3 percent, respectively.

At 12 months, the composite of thromboembolism, hemorrhagic stroke and death occurred in 8.7 percent of patients in the LAAO group and 13.5 percent of patients in the non-LAAO group. That represented a 21 percent reduction.

“Exploratory analyses suggest that the association between appendage occlusion and thromboembolism was strongest among those who are discharged without oral anticoagulation,” Friedman said during a press conference. “Although randomized trial data are needed, this study does support the concept of left atrial appendage occlusion at the time of cardiac surgery.”

The researchers cited a few limitations of the study, including its retrospective design. They also relied on claims data to determine the endpoints, and they had no data on the method or completeness of LAAO.

“There’s currently a wide variation in the use of this procedure at the time of cardiac surgery, largely due to the fact that there’s not good data on the safety or the efficacy of the procedure,” Friedman said in a news release. “While our 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.”