What does a LAA emptying velocity of less than 20 cm/sec typically indicate?

A left atrial appendage (LAA) emptying velocity of less than 20 cm/sec often suggests the presence of a thrombus. In a healthy heart, the LAA plays a significant role in the normal flow of blood, and adequate velocity indicates that the blood is moving effectively through this structure. When velocity drops below this threshold, it can imply stasis of blood flow, which greatly increases the risk of thrombus formation.

This situation is critical in the context of conditions like atrial fibrillation, where poor blood flow from the LAA can lead to clot formation, substantially raising the risk of stroke. Detecting an emptying velocity below this critical level is therefore a significant clinical finding that prompts further assessment and management to prevent complications associated with thrombi.