The left atrial appendage morphology is associated with embolic stroke subtypes using a simple classification system: A proof of concept study

Abstract Background and purpose The current left atrial appendage (LAA) classification system (cLAA-CS) categorizes it into 4 morphologies: chicken wing (CW), windsock, cactus, and cauliflower, though there is limited data on either reliability or associations between different morphologies and stroke risk. We aimed to develop a simplified LAA classification system and to determine its relationship to embolic stroke subtypes. Methods Consecutive patients with ischemic stroke from a prospective stroke registry who previously underwent a clinically-indicated chest CT were included. Stroke subtype was determined and LAA morphology was classified using the traditional system (in which CW = low risk) and a new system (LAA-H/L, in which low risk morphology (LAA-L) was defined as an acute angle bend or fold from the proximal/middle portion of the LAA and high risk morphology (LAA-H) was defined as all others). As a proof of concept study, we determined reliability for the two classification systems, and we assessed the associations between both classification systems with stroke subtypes in our cohort and previous studies. Results We identified 329 ischemic stroke patients with a qualifying chest CT (126 cardioembolic subtype, 116 embolic stroke of undetermined source (ESUS), and 87 non-cardioembolic subtypes). Intra- and inter-rater agreements improved using the LAA-H/L (0.95 and 0.85, respectively) vs. cLAA-CS (0.50 and 0.40). The LAA-H/L led to classifying 69 LAA morphologies that met criteria for CW as LAA-H. In fully adjusted models, LAA-H was associated with cardioembolic stroke (OR 5.4, 95%CI 2.1–13.7) and ESUS (OR 2.8 95% CI 1.2–6.4). Non-CW morphology was also associated with embolic stroke subtypes, but the effect size was much less pronounced. Studies using the cLAA-CS yielded mixed results for inter- and intra-rater agreements but most showed an association between a non-CW morphology and stroke with no difference among the three non-CW subtypes. Conclusion The LAA-H/L classification system is simple, has excellent intra and inter-rater agreements, and may help risk identify patients with cardioembolic stroke subtypes. Larger studies are needed to validate these findings.