Insight

Left Atrial Appendage Occlusion Reduces Thromboembolism Risk in Patients with Atrial Fibrillation
Catherine Amey, Senior Medical Writer, Touch Medical Media, Reading, UK

Atrial fibrillation, the most common sustained cardiac rhythm disorder, is associated with a substantial risk of mortality and morbidity from stroke and thromboembolism.1 The risk of thromboembolism was reduced by 40% in patients with atrial fibrillation who underwent left atrial appendage occlusion (LAAO) as an add-on during cardiac surgery, reports an observational study presented at the American College of Cardiology Scientific Session in Washington, DC, US.2

From an inverse probability weighted analysis of US Medicare data of 10,524 patients, around 37% underwent LAAO. Of these patients, 1.6% were hospitalised for thromboembolism within 12 months. This compared with 2.5% of patients who did not undergo the procedure and experienced thromboembolism. Further, LAAO was linked to a 15% reduction in the rate of death and a 21% reduction of the composite endpoint of thromboembolism, haemorrhagic stroke and death. Additional analysis showed that the most marked reduction in thromboembolism following LAAO occurred among patients not receiving anticoagulant medication at discharge. Patients taking anticoagulants at discharge showed no difference in their rates of thromboembolism. There was also no significant difference between patients undergoing LAAO and those who did not have the procedure on the rate of haemorrhagic stroke.

Medicare is a national database that includes 90% of cardiac surgery centres in the US. Data were extracted for Medicare patients with atrial fibrillation who underwent coronary artery bypass grafting, aortic valve surgery or mitral valve surgery in 2011 or 2012. In this study, 39% of patients were women and the median age was 76 years.

‘Intuitively, surgical left atrial appendage occlusion should work; however, there have been concerns that incomplete occlusion actually could lead to increased risk for thromboembolism because it could result in small communications between the appendage and the left atrium. The fact that we saw such a dramatic association between the procedure and a reduction in thromboembolism was reassuring that, at least in a more contemporary cohort of patients, left atrial appendage occlusion is able to be done in a much more effective way than initial reports had suggested may be the case,’ said lead investigator, Daniel J Friedman, a cardiology fellow at Duke Clinical Research Institute in Durham, North Carolina.

The observational nature of this analysis is a major limitation and a prospective, randomised controlled trial is needed to provide more robust evidence.

Funding
The study received funding from the Burroughs Wellcome Fund and the US Food and Drug Administration. Daniel J Friedman received funding from the National Institutes of Health T 32 training grant HL069749.

1. Lip GY, Nieuwlaat R, Pisters R, et al., Refining clinical risk stratification for predicting stroke and thromboembolism in atrial fibrillation using a novel risk factor-based approach: the euro heart survey on atrial fibrillation, Chest, 2010;137:263–72.
2. Friedman DJ, Comparative Effectiveness of Left Atrial Appendage Occlusion Among Atrial Fibrillation Patients Undergoing Cardiac Surgery: A Report From the Society of Thoracic Surgeons Adult Cardiac Surgery Database. Available at: www.acc.org/about-acc/press-releases/2017/03/18/08/47/sun-1045am-closing-left-atrial-appendage-reduces-stroke-risk-from-afib?w_nav=S#sthash.jOcNqixV.dpuf (accessed 2 May 2017).