Left Atrial Appendage Occlusion Shown to Reduce Risk of Stroke After Heart Surgery

May 15, 2021—Patients with an elevated risk of stroke caused by atrial fibrillation (AFib) were much less likely to experience a stroke after undergoing heart surgery if doctors concurrently performed a left atrial appendage occlusion (LAAO), according to findings from the LAAOS III study. All LAAO procedures in the study were performed through a standard surgical approach, so it is unclear whether catheter-based approaches for LAAO would bring the same benefits, advised the investigators.

The study’s lead author, Richard Whitlock, MD, a cardiac surgeon at McMaster University in Ontario, Canada, presented the LAAOS III results virtually at ACC.21, the American College of Cardiology’s (ACC) 70th annual scientific session. This study was simultaneously published online by Dr. Whitlock et al in The New England Journal of Medicine.

As summarized in a press release from the ACC, the study showed that LAAO lowered the risk of stroke or systemic embolism, the primary endpoint, by 33% overall in patients with AFib or atrial flutter. After the first 30 days following the procedure, patients who received LAAO were 42% less likely to have a stroke over long-term follow-up than those who did not receive LAAO. The trial was stopped early because of the strength of the observed benefits from the procedure.

LAAOS III investigators enrolled 4,811 patients undergoing heart surgery at 105 centers in 27 countries. Approximately two-thirds of the patients underwent valve surgery and 20% underwent coronary artery bypass graft surgery. All the patients had documented AFib or atrial flutter and a CHA2DS2-VASc score of two or higher, indicating an elevated risk of stroke. Half of the participants were randomly assigned to receive LAAO at the time of their heart surgery. All patients received standard anticoagulant medication to reduce the risk of harmful clots after surgery.

The investigators found that after a median follow-up of 3.8 years, 4.8% of patients who received LAAO and 7% of patients who did not receive LAAO had experienced a stroke, a difference that was highly significant in favor of LAAO. The difference was more pronounced after the first 30 days postsurgery. Strokes occurring soon after surgery typically have causes beyond AFib, such as calcium from blood vessels; thus, the true impact of LAAO on the risk of stroke from AFib is best seen after that early period, noted Dr. Whitlock in the ACC announcement.

The results were consistent across all subgroups analyzed, with LAAO bringing the same benefits regardless of geographic location, sex, age, type of AFib, type of blood thinner used, or other variables. On average, the procedure added less than 10 minutes to the heart surgery and demonstrated safety both in the short and long term.

“This study confirms a new paradigm for stroke prevention for patients with AFib,” commented Dr. Whitlock in the ACC press release. “The additive benefit of surgical LAAO on top of blood thinners has now been proven. There is no question that patients who are undergoing heart surgery and have elevated stroke risk and AFib should have their atrial appendage occluded in their cardiac surgery.”

Dr. Whitlock continued, “We were ecstatic to see these results. This trial opens a new option for treatment of these patients by layering a mechanical approach—occlusion—on top of a medical approach. Instead of a tension between anticoagulation and occlusion, we need to start thinking about using these as additive approaches when patients are at high risk for stroke. This is a procedure that’s done once, and it keeps giving a benefit over time. This is going to prevent thousands of strokes.”