eComment: Bilateral atrial appendage excision should be performed routinely in the surgical treatment of atrial fibrillation.

(eng) In the paper by Geuzebroek et al., the left atrial appendage was removed in all the patients, and the right atrial appendage was removed in bi-atrial maze (BAM) group. One of the goals of surgical treatment for atrial fibrillation is to alleviate the risk of systemic thromboembolism by preventing blood stasis in the left atrium, which leads to the development of mural thrombi. Studies have revealed that lower blood flow velocity in the left atrial appendage greatly increases the risk of thrombus formation and the incidence of stroke . Clinical experience, however, documents that although left atrial thrombi are a common occurrence in atrial fibrillation, right atrial thrombi are not. Differences in the right atrial and left atrial anatomy probably explain these clinical patterns. For example, the orifice of the right atrial appendage is so broad-based that it is not usually thought of as being an orifice at all. Moreover, this wide-open entrance into the relatively shallow right atrial appendage is located immediately adjacent to the stream of blood flow from the superior vena cava into the right atrium and across the tricuspid valve. Therefore, there is little opportunity for stasis of blood within the body of the right atrial appendage, even when the atrium is fibrillating. On the contrary, the orifice of the left atrial appendage is an identifiable anatomic opening in virtually all patients. This narrow orifice leads into a relatively long narrow lumen of the left atrial appendage, which is eccentric to the stream of blood flow from the pulmonary veins to the mitral valve. Therefore, when the atrium is fibrillating, severe stasis of blood in the left atrial appendage is virtually assured and is one of the major factors resulting in thrombus formation in the left atrial appendage. The atrial appendage has been shown to secrete atrial natriuretic peptides and reduced secretion of these peptides has been demonstrated in patients after maze procedure with bilateral atrial appendage excision. This reduced secretion of natriuretic peptides could be one of the mechanisms for the postoperative complication of fluid retention frequently seen after the maze procedure. We believe that to preserve secretion of atrial natriuretic peptides, the right and left atrial appendage should be preserved, but the left atrial appendage should be excluded by an interior or exterior continue suture line because it is the most common region for development of mural thrombus.