LAAOS III: Left Atrial Appendage Occlusion Cuts Stroke Risk in Patients with Atrial Fibrillation


Results of the LAAOS III trial provide evidence suggesting left atrial appendage occlusion could reduce risk of ischemic events by nearly a third and also reduce risk of stroke by more than 40% in patients with atrial fibrillation.

Richard Whitlock, MD, PhD,  McMaster University

Richard Whitlock, MD, PhD

Occlusion of the left atrial appendage during cardiac surgery could slash the risk of stroke in patients with atrial fibrillation (AF), according to new data presented at the American College of Cardiology’s 70th Annual Scientific Session (ACC.21).

The Left Atrial Appendage Occlusion Study (LAAOS) III trial, results of the study indicate left atrial appendage occlusion was associated with a 33% reduction in ischemic events and reduced the long-term risk of stroke by 42% among patients with AF.

“This study confirms a new paradigm for stroke prevention for patients with atrial fibrillation,” said lead investigator Richard Whitlock, MD, PhD, a cardiac surgeon at McMaster University in Ontario, in a statement. “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 atrial fibrillation should have their atrial appendage occluded in their cardiac surgery.”

After LAAOS I and LAAOS II provided evidence suggesting left atrial appendage occlusion could reduce risk of stroke in patients with atrial fibrillation undergoing cardiac surgery, LAAOS III was designed to evaluate the clinical efficacy of left atrial appendage occlusion in a larger study population. With his in mind, the trial enrolled nearly 5000 patients with AF undergoing a cardiac surgery for another indication from 105 centers in 27 countries and randomized them in a 1:1 ratio to undergo left atrial appendage occlusion or no occlusion.

Patients included in the trial had follow-up assessments occur at 30 days and then every 6 months after. As part of the trial design, all patients received usual care and oral anticoagulation after surgery. For the purpose of analysis, the primary outcome was defined as the occurrence of ischemic stroke or systemic embolism.

In total, 2379 patients were randomized to occlusion and 2391 were randomized to the no occlusion group. The mean age of the entire study population was 71 years and the mean follow-up time was 3.8 years. Of note, all patients included had AF and a CHA2DS2-VASc score of at least 2—the mean CHA2DS2-VASc score at baseline was 4.2.

Upon analysis, investigators found 92.1% of patients received the assigned procedure and, at 3 years, 76.8% of patients continued to receive oral anticoagulation. Among those randomized to occlusion, occlusion was attempted in 89.6% (n=2131) patients. The most common occlusion method was cut and sew (55.7%) followed by closure device (15.1%), closure from within (13.8%), stapler (11.2%), and other approved techniques (4.1%).

When assessing the primary outcome, results indicated stroke or systemic embolism occurred in 4.8% (n=114) of patients in the occlusion group and 7.0% (n=168) of patients in the no occlusion group (HR, 0.67; 95% CI, 0.53-0.85; P=.001). Among individual components of the primary outcome, ischemic stroke occurred among 4.6% (n=109) in the occlusion group and 6.9% (n=164) in the no occlusion group (HR, 0.66; 95% CI, 0.52-0.84).

When assessing safety endpoints, investigators found there were no significant differences in rate of mortality ([22.6% vs 22.5%]; HR, 1.00; 95% CI, 0.89-1.13), hospitalization for heart failure ([7.7% vs 6.8%]; HR, 1.13; 95% CI, 0.92-1.40), or incidence of major bleeding events ([10.4% vs 11.2%] HR, 0.93; 95% CI, 0.78-1.11) between the occlusion and no occlusion arms, respectively.

“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.”

This study, "Left Atrial Appendage Occlusion during Cardiac Surgery to Prevent Stroke,” was presented at ACC.21 and simultaneously published in the New England Journal of Medicine

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