Patients with atrial fibrillation at risk of stroke could be offered percutaneous closure of the left atrial appendage instead of long-term warfarin therapy. The findings, from the PROTECT AF study, are reported in an Article in this week's edition of The Lancet, written by Professor David R Holmes, Mayo Clinic, Rochester, MN, USA, and colleagues.
Atrial fibrillation is the most common sustained cardiac arrhythmia (irregular heartbeat), and its prevalence is expected to increase as the world's populationages. Atrial fibrillation causes the upper chambers of the heart to quiver, this can cause blood to pool and form blood clots in an area of the heart called the left atrial appendage (LAA). The LAA, an embryonic remnant of the original left atrium, is a long, tubular structure that is connected to the left atrial cavity. More than 90% of atrial thrombi in patients with non-valvular atrial fibrillation are believed to originate in the LAA. In this randomised study, the authors assessed the efficacy and safety of percutaneous closure of the LAA compared with long term warfarin therapy in patients with non-valvular atrial fibrillation at risk for stroke.
Patients were eligible for the study if they had at least one of the following: previous stroke or transient ischaemic attack*, congestive heart failure, diabetes, high blood pressure, or were 75 years or older. A total of 707 patients were randomised in a 2:1 ratio to percutaneous closure of the LAA and subsequent discontinuation of warfarin (463 patients) or to long term warfarin therapy (244 patients). The percutaneous procedure involved implantation of a device (the WATCHMAN) to close off the LAA. Efficacy was assessed through a combined endpoint of all stroke (ischeamic and haemorrhagic), cardiovascular death, and systemic embolism (a blood clot that goes somewhere other than the brain). Serious adverse events that were part of the safety assessment included major bleeding, pericardial effusion (an accidental puncture of the heart causing fluid collection in the heart sac), and device embolisation.
The authors found that after 1065 patient years of follow up, there were 3.0 efficacy events per 100 patient-years in the device group, compared with 4.9 in the warfarin group—a relative reduction of 38%. However, serious safety events were more common in the device group (7.4 events per 100 patient-years) compared with the warfarin group (4.4); most of these safety events were related to the procedural implant.
The authors conclude: "The efficacy of percutaneous closure of the LAA with this device was non-inferior to that of warfarin therapy. Although there was a higher rate of adverse safety events in the intervention group than the control group, events in the intervention group were mainly a result of periprocedural complications. Closure of the LAA might provide an alternative strategy to chronic warfarin therapy for stroke prophylaxis in patients with non-valvular atrial fibrillation."
In an accompanying Comment, Drs Dominick J H McCabe, Justin A Kinsella, and W Oliver Tobin, Adelaide and Meath Hospital, Dublin, incorporating the National Children's Hospital, Trinity College, Dublin, Ireland, say that despite its limitations, warfarin is still the treatment of choice for patients with non-valvular atrial fibrillation who have clear indications for, and who are suitable for long-term oral anticoagulation. However they add that further research is warranted into the use of left atrial appendage occlusion devices, particularly for patients unsuitable for long term warfarin therapy.
Professor David R Holmes, Mayo Clinic, Rochester, MN, USA T) +1 507-255-5846 E) holmes.david@mayo.edu
Dr W Oliver Tobin, Adelaide and Meath Hospital, Dublin, incorporating the National Children's Hospital, Trinity College, Dublin, Ireland T) +353 1 414 4217E) oliver.tobin@yahoo.co.uk
For full Article and Comment, see: http://press.thelancet.com/laa.pdf
Notes to editors: *Transient ischaemic attack=a blockage of blood vessels in the brain not as serious as a stroke
Journal
The Lancet