Abstract WP261: The Left Atrial Septal Pouch: A New Stroke Risk Factor?

Abstract

Background: The left atrial septal pouch (LASP) is a common anatomic variant produced by the incomplete fusion of septa primum and secondum at the inter-atrial septum, thus creating a potential embolic source from an open flap or blind pouch in the left atrium. Our prior work demonstrated increased prevalence of LASP in cryptogenic strokes (Frontiers Neurology 3-24-15). The aim of the current study was to examine the prevalence of LASP in a separate, more recent group of stroke patients and control subjects who underwent transesophageal echocardiography (TEE). Methods: We examined consecutive TEE studies performed between July, 2011 and December, 2018 at UC Irvine Medical Center. Prevalence of LASP was determined in TEE studies referred for ischemic stroke or TIA (“stroke subjects”), and compared to LASP prevalence in patients undergoing TEE for other reasons (“control subjects”). Stroke subtyping was performed using TOAST (Trial of Org 10172 in Acute Stroke Treatment) criteria. Results: TEE studies were performed on 221 cerebrovascular cases and 164 control subjects. Age and sex were 57±1 years (mean±SE) and 53% male for stroke subjects, and 56±1 years and 62% male for control subjects. Prevalence of LASP was 24% (40/164) in control subjects, 17% (24/138) in non-cryptogenic stroke subjects, and 36% (30/83) in cryptogenic stroke subjects. LASP prevalence was significantly higher for cryptogenics compared to the other groups (p=0.007). There was no significant difference between LASP prevalence in controls vs non-cryptogenic stroke. Elimination from analysis of subjects with other inter-atrial septal abnormalities (ie, patent foramen ovale or atrial septal defect) did not significantly change results. Conclusions: These findings demonstrate an increased prevalence of LASP in cryptogenic stroke, confirming our prior published findings. Given the plausibility of LASP acting as a thromboembolic nidus, additional studies are needed to determine the generalizability of these findings and their therapeutic implications.