The left atrial appendage: An enigmatic friend or foe and implications of closure.

The left atrial appendage (LAA) is often thought of as a vestigial organ serving as a nidus for clot formation in those with atrial fibrillation (A-fib). The LAA, however, has unique anatomy which allows it to serve special functions in the human body. Closing the LAA has been shown to decrease the risk of thromboembolic events in patients who cannot tolerate anticoagulation. Several methods of closure exist including percutaneous endocardial closure, epicardial closure, and surgical clipping. In addition to decreasing stroke risk, there appears to be physiologic changes that occur after LAA closure. This comprehensive review aims to describe the functions of the LAA, compare the different methods of closure, and propose a new method for identifying which patients may benefit from LAA closure versus anticoagulation based on each patients' individual comorbidities rather than their contraindications.