Patients with atrial fibrillation undergoing cardiac surgery should have concomitant atrial appendage occlusion, according to a new study presented at the American College of Cardiology 2021 Scientific Sessions.
“We have shown that left atrial appendage occlusion is not only a viable option but should be standard of care for patients with atrial fibrillation undergoing cardiac surgery,” says Dr. Richard Whitlock, primary investigator of the LAAOS III trial, a cardiovascular surgeon and professor of surgery at McMaster University. The results of LAAOS III were concurrently published in the New England Journal of Medicine .
While left atrial appendage occlusion had previously been hypothesized to reduce stroke in patients with atrial fibrillation, the procedure has never proven to be effective in a large, randomized clinical trial. Dr. Whitlock and the team of investigators for LAAOS III sought to investigate whether this is true. In the multinational, multicenter trial, investigators enrolled 4,811 participants with atrial fibrillation who were undergoing cardiac surgery to receive either a concomitant left atrial occlusion procedure, or standard non-surgical therapy for atrial fibrillation. The primary outcome of the trial was the first occurrence of ischemic stroke or noncerebral systemic embolism. The primary safety endpoint was hospitalization for heart failure, given prior concerns that left atrial occlusion would cause decreased levels of circulating atrial natriuretic peptide, provoking heart failure symptoms.
All participants had a CHADS-VASC score of at least 2, with a mean age of 71 years and mean CHADS-VASC of 4.2. Those undergoing surgical occlusion received one four prespecified techniques: amputation and closure, stapler closure, double layer linear closure, or closure with an approved occlude device.
Almost all participants were maintained on oral anticoagulants at hospital discharge, with approximately 80% adherence at three years in both arms. After the first 30 days, the primary outcome event occurred in 2.7% of the occlusion group and 4.6% of the non-occlusion group, with a hazard ratio of 0.58. There was no significant difference in death, bleeding, or heart failure in either group. Given the definitive results at the second interim analysis, the data safety monitoring board recommended an end to the trial and public reporting of the data.
The authors recognize some limitations of the study, namely a lack of information about relative efficacy of left atrial appendage occlusion when compared to oral anticoagulation alone. Furthermore, the study only included patients undergoing cardiac surgery, and could not be extrapolated to those receiving endovascular left atrial occlusion therapies, or those receiving stand-alone occlusion.
When asked about future implications of this trial, Dr. Whitlock stated “Direct oral anticoagulants have been widely adopted and will only continue to be improved upon in the near future. Our results show that there is benefit to occlusion for patients who can tolerate OACs, but for those who cannot, the study demonstrates benefit as well. I hope that this study opens the door for the investigation of more surgical and endovascular techniques in the treatment of atrial fibrillation for all patients with atrial fibrillation, not just those who cannot tolerate OACs”.
Funded by the Canadian Institutes of Health Research and others; LAAOS III ClinicalTrials.gov number, NCT01561651.