Association found between left atrial appendage closure and readmission for thromboembolism

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A collaborative study, has found that older patients with atrial fibrillation (AF) undergoing cardiac surgery accompanied with surgical left atrial appendage closure had a lower risk of readmission for thromboembolism over the following 3 years. The study was carried out at at Duke University, Northwestern University, Mayo Clinic, Cleveland Clinic Foundation, Baylor University, West Virginia University and the Johns Hopkins All Children’s Heart institute, all in the USA.

The study took place over three years, with the aim of being to evaluate the association of surgical left atrial appendage closure (S-LAAC) vs no receipt of S-LAAC with the risk of thromboembolism among older patients undergoing cardiac surgery. The results are published in the Journal of the American Medical Association.

“Our report represents the largest and most convincing study that use of left atrial appendage occlusion at the time of concomitant cardiac surgery may be an effective means to reduce stroke and mortality in this high risk patient cohort.” said Daniel J Friedman, lead author, “However, given the observational nature of our study, randomised controlled trials will be necessary to demonstrate a cause and effect relationship between left atrial appendage occlusion and improved clinical outcomes.”

The left atrial appendage is an important sight of thrombus formation in atrial fibrillation and can be occluded or removed during cardiac surgery. Before this study began there was inconclusive evidence regarding the effectiveness of S-LAAC in reducing the risk of thromboembolism.

Designed as a retrospective cohort study and to be representative of the US population, a Medicare-linked cohort of 10,524 patients from the Society of Thoracic Surgeons Adult Cardiac Surgery Database (2011- 2012), was used. Patients aged 65 years or more undergoing cardiac surgery (defined as coronary artery bypass grafting, mitral valve surgery with or without coronary artery bypass grafting or aortic valve surgery with or without coronary artery bypass grafting) with or without accompanying S-LAAC were followed until the end of 2014.

The patients had a median age of 76 years, were 29% female and had a median CHA2DS2-Vasc score of 4. Of the 10,524 patients followed 3,892 underwent S-LAAC.

The primary outcome was readmission for thromboembolism (stroke, transient ischemic attack, or systemic embolism) at up to 3 years of follow-up and the secondary end points included haemorrhagic stroke, all-cause mortality, and a composite end point (thromboembolism, haemorrhagic stroke, or all-cause mortality).

At a mean follow-up of 2.6 years, thromboembolism had developed in 5.4% of patients, haemorrhagic stroke had occurred in 0.9% of the group, all-cause mortality in 21.5%, and the composite end point of thromboembolism, haemorrhagic stroke or all-cause mortality had occurred in 25.7% of patients.

S-LAAC, compared with no S-LAAC, was associated with lower unadjusted rates of thromboembolism (4.2% vs 6.2%), all-cause mortality (17.3% vs 23.9%), and the composite end point (20.5% vs 28.7%) but no significant difference in rates of haemorrhagic stroke (0.9% vs 0.9%) was observed. After inverse probability-weighted adjustment, S-LAAC was associated with a significantly lower rate of thromboembolism (subdistribution hazard ratio [HR], 0.67; 95% CI, 0.56-0.81; P < .001), all-cause mortality (HR, 0.88; 95% CI, 0.79-0.97; P = .001), and the composite end point (HR, 0.83; 95% CI, 0.76-0.91; P < .001) but not haemorrhagic stroke (subdistribution HR, 0.84; 95% CI, 0.53-1.32; P = .44). S-LAAC, compared with no S-LAAC, was associated with a lower risk of thromboembolism among patients discharged without anticoagulation (unadjusted rate, 4.2% vs 6.0%; adjusted subdistribution HR, 0.26; 95% CI, 0.17-0.40; P < .001), but not among patients discharged with anticoagulation (unadjusted rate, 4.1% vs 6.3%; adjusted subdistribution HR, 0.88; 95% CI, 0.56-1.39; P = .59).

Overall, the group suggest that they’re findings support the use of S-LAAC, but that randomised trials are necessary to provide definitive evidence.

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