Left atrial appendage (LAA) closure at the time of cardiac surgery may reduce the risk of thromboembolism in older patients with atrial fibrillation (AFib), according to an observational study published in the Journal of the American Medical Association.

AFib, the most common sustained arrhythmia, has been associated with an increased risk of thromboembolic stroke. Oral anticoagulation is known to reduce the risk of stroke, but only half of eligible patients may take the medication due to high perceived hemorrhage risk, cost and patient preference, noted lead researcher Daniel J. Friedman, MD, and colleagues.

“The low rates of anticoagulant use and the understanding that AFib-related thrombus formation is most likely to occur in the LAA has led to increasing interest in occluding the LAA as a potential alternative to anticoagulation, particularly among those with difficulty tolerating anticoagulation,” the researchers wrote.

Friedman et al. studied 10,524 Medicare recipients with atrial fibrillation undergoing cardiac surgery—coronary artery bypass grafting (CABG), mitral valve surgery, aortic valve surgery, or a combination of CABG and valve surgery. The median age of the study population was 76 and 39 percent were female.

Thirty-seven percent of the patients underwent surgical left atrial appendage occlusion (S-LAAO). At a mean follow-up of 2.6 years, fewer of those patients experienced thromboembolism (4.2 percent vs. 6.2 percent) and all-cause mortality (17.3 percent vs. 23.9 percent). Rates of hemorrhagic stroke were 0.9 percent in both groups.

After propensity-score adjustment, Friedman et al. found the risk of thromboembolism was significantly lower in S-LAAO patients discharged without anticoagulant therapy compared to patients who received neither S-LAAO nor anticoagulation. However, there was no significant difference in thromboembolic risk in patients discharged with anticoagulation, whether they received S-LAAO or not.

“The observed association between S-LAAO and lower rates of thromboembolism may have been primarily related to lower observed rates of thromboembolism in the substantial group of patients discharged without anticoagulation,” the authors wrote. “While observational in nature, this analysis supports the use of S-LAAO in patients with AFib at the time of cardiac surgery.”

Friedman and colleagues acknowledged several key limitations. For one, treatment patterns weren’t randomized. In addition, they were unable to determine patient adherence to oral anticoagulants or the duration of treatment, both of which may have affected outcomes. Finally, most of the patients discharged with anticoagulation received warfarin so the results may not apply to other anticoagulants.

In a related editorial, Victor A. Ferraris, MD, PhD, said the researchers raised the “intriguing” possibility S-LAAO could prevent thromboembolism just as well as anticoagulation without anticoagulants’ excess risk of major bleeding.

“This somewhat novel hypothesis, if true, could avoid a significant morbidity associated with anticoagulation while providing adequate treatment for thromboembolic complications of AFib,” wrote Ferraris, with the department of surgery at the University of Kentucky. “The findings reported by Friedman and coauthors may help guide clinical practice and should serve to contribute to safer surgical approaches for AFib treatment among patients who require cardiac operations.”