The left atrial appendage (LAA) is the most common site of thrombus formation in patients with atrial fibrillation. Therefore, better knowledge of the morphology, physiology, and function of the LAA may provide a better estimate of stroke risk. The LAA morphology is currently classified into 4 categories: chicken-wing (CW), windsock, cauliflower, and cactus. Chicken-wing is the most common and carries lower risk. This classification system, however, lacks consistent inter-rater reliability and correlation with stroke risk.