Left atrial appendage anatomy: clinical implications for cardiac procedures

The Left Atrial Appendage (LAA) is the most common source of thrombi during atrial fibrillation (AF) leading to stroke. With the increasing prevalence of AF and the growing number of patients requiring LAA involved interventions like exclusion and ablation, understanding LAA's anatomical intricacies becomes paramount importance. This study aims to provide anatomical data regarding LAA in relation to these procedures. Total 50 formalin-fixed cadaveric hearts were examined and various morphological and morphometric parameters were noted. The Cauliflower shape LAA (36%) was most common followed by Chicken Wing (34%), Cactus (18%), and Windsock (12%) shapes. The LAA orifice had greater horizontal diameter compared to the vertical diameter and was oval in shape in 64% cases. Diverticular structures called divots/ pits were present surrounding the LAA orifice in 36% cases with high variation in number, size, and distance from orifice. They were most commonly present towards the septal side and posterior wall side around the LAA orifice. The circumflex artery was the closest structure to LAA orifice with less than 5 mm distance in 76% cases. Other structures present close to the LAA were the Left Superior Pulmonary Vein and Mitral Valve. According to shape, the Non-Chicken Wing morphology of the LAA was associated with close running left circumflex artery, high OI (Ovality Index) of the orifice, and greater presence of divots. The LAA anatomy is complex with high amount of variability making it difficult to perform successful procedures. Given data can help clinicians in better planning and execution of cardiac interventions involving the LAA.