Incidence and clinical relevance of left atrial appendage membranes: a new congenital heart disease?

Abstract

Aims Left atrial appendage (LAA) membranes are rare congenital anomalies. Those involving the appendage orifice may obstruct its emptying flows, thus promoting blood stasis and clot formation. However, the epidemiology of LAA membranes has never been studied and a correlation with appendage thrombosis has never been proved. Very few case reports described LAA membranes, therefore, their frequency and clinical significance are not known. Moreover, their presence and degree are of crucial importance in planning LAA percutaneous closure, a procedure whose indication is evolving, and whether their presence can represent technical issues during the device implantation is not known. This study aimed to evaluate the incidence and the clinical significance of LAA membranes. Methods and results A population of 6030 consecutive transoesophageal echo (TOE) studies has been retrospectively reviewed in order to find those patients in whom an LAA membrane has been found. A literature research has been performed to review previous described cases. Among 6030 TOE cases, an LAA membrane has been described in 6 (prevalence of 1/1000). In one case, the membrane was associated to a severe LAA hypoplasia and in another case to an LAA thrombus (these represent the first cases ever described). All patients had an atrial fibrillation (AF) history and two were in AF during the TOE exam. Conclusion LAA membranes are rare congenital abnormalities occasionally discovered during a TOE exam, frequently in patients affected by AF. In half of the cases, they obstruct the LAA flow, thus theoretically pre-disposing to clot formation. They may be rarely associated to an appendage hypoplasia. During a TOE exam, cardiac imagers should always rule out their presence.

Congenital left atrial appendage ostial stenosis in an extremely premature infant diagnosed by transthoracic echocardiography

“…The prevalence of LAAOS is not well established, but a retrospective review of adults with atrial fibrillation found a prevalence of LAA membranes of 1 per 1000, only half of which caused obstruction. 3 While reported as a congenital anomaly, the authors did not have long term serial imaging to support this claim in a population of adults.…”

“…The clinical significance of LAAOS is not clear. Due to the known risk of thrombus formation in the LAA, LAAOS has been proposed to further increase this risk secondary to compromised flow and potential stasis caused by the membrane 3,4,6 . Interestingly, some have argued that even if there is thrombus formation within the LAA, the smaller orifice due to LAAOS could be protective.…”

“…1,2 LAAOS has been defined as a membrane at least one-third of the ostial diameter, to differentiate it from imaging artifacts or embryonic remnants of no hemodynamic significance. 3 The abnormal flow into and out of the LAA can be a source of thrombus formation in the systemic atrium. We present a case of LAAOS in an extremely premature infant diagnosed while undergoing evaluation for catheter-based patent ductus arteriosus (PDA) closure.…”

“…First reported in 1999, there have only been a small number of cases reported, almost exclusively in adults and one young child 1,2 . LAAOS has been defined as a membrane at least one‐third of the ostial diameter, to differentiate it from imaging artifacts or embryonic remnants of no hemodynamic significance 3 . The abnormal flow into and out of the LAA can be a source of thrombus formation in the systemic atrium.…”

Multimodality Imaging in Diagnosing Left Atrial Appendage Atresia of the Ostium

“…Finally, using 3D image, they confirmed the narrowed LAA orifice. Cresti et al 2 demonstrated that the prevalence of LAA membranes was 1 of 1000 in their study. Those involving the appendage orifice may obstruct its emptying flows, thus promoting blood stasis and clot formation.…”