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The cornerstone of atrial fibrillation (AF) management is effective stroke prevention, which by now remains the only proven method of improved survival in patients with AF. Oral anticoagulation with the use of vitamin K antagonists (eg, warfarin) or non-vitamin K antagonist oral anticoagulants (NOACs) has been shown to substantially reduce the risk of AF-related strokes and thus is presently the standard of care for stroke prevention in non-valvular AF.
Approximately 90% of thrombi being formed in AF are localised in left atrial appendage (LAA).1 Thus, LAA exclusion seems a tempting method of prophylaxis against stroke, particularly if antithrombotic therapy could be utterly omitted to eliminate the risk of bleeding complications. Though the history of LAA occlusion dates back many years, it is more recent rapid developments and implementation of various percutaneous approaches to LAA closure.
What is the evidence for LAA closure?
There have been two prospective randomised non-inferiority trials (RCTs) on LAA exclusion.
Watchman Left Atrial Appendage System for Embolic Protection in Patients with AF (PROTECT AF) randomised patients in a 2:1 ratio to receive either Watchman device or warfarin (table 1). At 2 years follow-up, trial showed non-inferiority of LAA closure to warfarin. After 4 years of observation, LAA exclusion met prespecified criteria for both non-inferiority and superiority compared with warfarin.2 Despite these optimistic efficacy findings, the rate of periprocedural complications was high at 8.7% (table 1). Importantly, though LAA occlusion was superior to warfarin in the prespecified primary efficacy endpoint (composite of stroke, systemic embolism and cardiovascular/unexplained death), it did not meet the non-inferiority criteria for ischaemic stroke risk reduction (table 1). Indeed, there were less ischaemic strokes in warfarin group and superiority of LAA closure over warfarin was predominantly driven by lower incidence of haemorrhagic strokes in the device arm. A closer inspection of mortality reasons also shows that only death rates resulting …
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