Left atrial appendage occlusion during cardiac surgery reduces stroke risk
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In the LAAOS III trial, concomitant left atrial appendage occlusion during cardiac surgery for another indication reduced the risk for ischemic stroke and systemic embolism in patients with atrial fibrillation.
“Surgical left atrial appendage occlusion reduced ischemic stroke by 33%. After the first high-risk perioperative period of 30 days, the effect was more pronounced, with a reduction of 42%,” Richard Whitlock, MD, PhD, cardiac surgeon at McMaster University in Ontario, Canada, said during a late-breaking clinical trial presentation at the American College of Cardiology Scientific Session.
The trial was stopped early due to the strength of the observed benefits of the procedure.
LAAOS III enrolled 4,811 patients in 27 countries worldwide who had AF and a CHA2DS2-VASc score of at least 2 with planned cardiac surgery for another indication. Half were assigned to undergo left atrial appendage (LAA) occlusion at the time of cardiac surgery and half underwent cardiac surgery only. All patients were receiving usual care, including oral anticoagulation.
This was a high-risk group for stroke, Whitlock said. The mean age was 71 years, two-thirds were men, half had paroxysmal AF and the mean CHA2DS2-VASc score was 4.2.
Only 20% of the patients underwent isolated CABG. One-third underwent an ablation procedure. Two-thirds underwent some type of valve procedure, which Whitlock said “makes LAAOS III unique in that many previous AF trials have excluded valvular AF.”
The addition of LAA occlusion to cardiac surgery for other reasons resulted in a small increase in bypass time (119 minutes vs. 113 minutes; P < .001) and cross-clamp time (86 minutes vs. 82 minutes; P < .001). It did not increase chest tube output, need for reoperation for bleeding, prolongation of hospitalization due to HF or 30-day mortality, according to the results.
On discharge, 83.4% of the LAA occlusion group and 81% of the no-occlusion group were receiving oral anticoagulation. This decreased to 75.3% and 78.2%, respectively, at 3 years.
“The benefit of left atrial appendage occlusion is additive to oral anticoagulation,” Whitlock said.
During the mean follow-up of 3.8 years, the primary endpoint of ischemic stroke or systemic embolism occurred in 4.8% of patients who underwent LAA occlusion during cardiac surgery compared with 7% of those who underwent cardiac surgery only (HR = 0.67; 95% CI, 0.53-0.85; P = .001). Kaplan-Meier curves demonstrated an early and ongoing benefit of LAA occlusion, Whitlock said. During the first 30 days, ischemic stroke or systemic embolism occurred in 2.2% of the LAA occlusion group vs. 2.7% of those who underwent cardiac surgery only (HR = 0.82; 95% CI, 0.57-1.18), and after 30 days, the incidence was 2.7% and 4.6%, respectively (HR = 0.58; 95% CI, 0.42-0.8).
The researchers reported no differences in perioperative bleeding, HF or death between patients who did or did not undergo LAA occlusion.
In other results, the effect of LAA occlusion on risk for stroke or systemic embolism was consistent across subgroups, including age, sex, type of oral anticoagulation at baseline, type of cardiac surgery and CHA2DS2-VASc score.
“The results of LAAOS III have important implications for the use of nonpharmacologic therapies to prevent embolic stroke. In our trial, surgical occlusion of the left atrial appendage provided additional protection against stroke when added to anticoagulation,” Whitlock and colleagues wrote in The New England Journal of Medicine.
In a related editorial published in NEJM, Richard L. Page, MD, with the division of cardiovascular medicine at Robert Larner College of Medicine at University of Vermont, said the LAAOS III trial “provides important answers, even as it raises questions.”
“On the basis of the demonstrated benefit with no discernible risk, surgical left atrial appendage occlusion should be performed at the time of other cardiac surgery in patients with atrial fibrillation and a CHA2DS2-VASc score of at least 2, with anticoagulation continued thereafter. The major clinical practice guidelines will probably include these new data and the conclusion they imply, perhaps with a class I recommendation for the population studied.”
References:
- Page RL. N Engl J Med. 2021;doi:10.1056/NEJMe2106069.
- Whitlock RP, et al. N Engl J Med. 2021;doi:10.1056/NEJMoa2101897.
Perspective
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Satish Misra, MD
The size and design, specifically blinding to LAA occlusion in follow-up, are impressive. That there was additive benefit on top of oral anticoagulation was surprising, but reinforces findings in other studies that the benefit of oral anticoagulation is not simply preventing thrombus formation in the LAA. While practice changes should await complete publication of the results, I suspect this trial will make LAA occlusion more appealing at the time of cardiac surgery, particularly given the good safety profile. An important unanswered question is in what scenarios, if any, can anticoagulation be discontinued after surgical LAA occlusion. Subgroup analysis from this study may help in that regard as well.
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Whitlock R, et al. Joint American College of Cardiology/Journal of American College of Cardiology Late-Breaking Clinical Trials. Presented at: American College of Cardiology Scientific Session; May 15-17, 2021 (virtual meeting).
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