Key takeaways

• Closing off a small pouch in the heart where clots form – called the left atrial appendage – is recommended in patients undergoing open-heart surgery who have atrial fibrillation to reduce stroke risk.

• The LAACS-2 trial investigated whether all patients undergoing open-heart surgery may benefit from left atrial appendage closure.

• The results did not support closure in all patients but those at high risk of stroke appeared to benefit.

• Long-term follow-up of patients continues.

Munich, Germany – 31 August 2026: Results do not support routine closure of the left atrial appendage in all patients undergoing open-heart surgery but those at high stroke risk may benefit. This was the main conclusion of the LAACS-2 trial presented in a Hot Line session today at ESC Congress 2026.¹

Following open-heart surgery, patients face a high long-term risk of stroke. The left atrial appendage (LAA) is a small muscular pouch in the heart’s left atrium, which is known to be a common source of blood clots in patients who have atrial fibrillation (AF). Surgical closure of the LAA is recommended in ESC Guidelines as an adjunct to oral anticoagulation for patients with AF undergoing cardiac surgery.² However, evidence is lacking in patients without a known history of AF.

Associate Professor Helena Dominguez from Bispebjerg University Hospital, Copenhagen, Denmark and colleagues previously conducted the LAACS trial in patients undergoing open-heart surgery. She noted: “With long-term follow-up, we observed lower risk of stroke after LAA closure whether the patient had AF or not.^3,4 We conducted the much larger LAACS-2 trial to further investigate if LAA closure has a protective effect in patients with, but mostly without, prior AF.”

The LAACS-2 trial was conducted across four sites in Denmark, Spain and Sweden. Patients undergoing first-time planned open-heart surgery without AF and those with a previous diagnosis of paroxysmal or chronic AF were included. A total of 1,500 patients were randomised (1:1) to either concomitant LAA closure or standard care (open LAA). The mean age was 67 years and 18.5% were female. Before surgery, 4.1% had AF, 6.1% had prior stroke and 2.5% had prior transient ischaemic attack.

Across a median of 4.0 years’ follow-up, there was no significant difference in the primary outcome of stroke or transient ischaemic attack with LAA closure vs. standard care (4.28% vs. 5.04%, respectively; hazard ratio 0.85; 95% confidence interval 0.53 to 1.37; p=0.517).

Of note, patients who had the highest stroke risk at baseline (CHA2DS2-VASc score above the median) had a 56% reduction in the primary endpoint with LAA closure (p=0.018), while no significant benefit was observed in those with lower stroke risk.

Overall, there was no significant difference in mortality between the groups.

“Our results do not support routine LAA closure in all patients undergoing planned cardiac surgery. However, closure appeared to confer protection in patients at high risk of stroke,” concluded Associate Professor Dominguez. “As we saw in the LAACS trial, the primary endpoint curves diverged over time in LAACS-2 and follow-up will be continued.” Associate Professor Dominguez highlighted an ongoing mechanistic study that aims to further understand stroke risk following LAA closure in patients undergoing open-heart surgery.⁵

ENDS