Left atrial appendage closure for prevention of cardioembolic events

Atrial fibrillation (AF) is the most common atrial arrhythmia, with a prevalence of 1-2% in the general population. It increases with age, affecting approximately 7% of individuals age >65 years and 15-20% of octogenarians. The human left atrium has a blind sac-like remnant, called left atrial appendage (LAA). It originates from a primordial pulmonary vein. Due to its complicated structure, blind end and inner surface trabeculated by pectinate muscles, thrombi in nonvalvular AF form almost exclusively in the LAA and not in the smooth-walled left atrium. For the last 50 years, oral anticoagulation (OAC) with vitamin K antagonists (VKAs) has been the only treatment option to prevent stroke and systemic embolism from thrombi in AF. More recently, non-vitamin K-dependant oral anticoagulants (NOACs) have been shown to be noninferior or even superior to VKA with respect to efficacy and safety. In light of the limitations of indefinite OAC, particularly among patients at increased risk for bleeding and because thrombi arise predominantly from the LAA among AF patients, exclusion of the LAA with closure devices (LAAC) provides a novel treatment strategy for prevention of stroke and bleeding. Recently, LAAC has been compared with VKA therapy in prospective randomised trials with promising results. Today, the decision to provide the most appropriate treatment for a patient with AF (OAC, NOAC or LAAC) is complex and needs to be individualised. This review provides an update on the current state of LAAC in the field of stroke prevention in patients suffering from nonvalvular AF. We describe the pathophysiology of the LAA with regard to stroke. Aside from the evidence and limitations of anticoagulation as the classical treatment paradigm for stroke prevention, devices and techniques for LAAC are outlined and the current clinical evidence with regard to efficacy and safety is reviewed. Finally, contemporary recommendations for patient selection are provided.