Abstract 10688: The Association of Atrial Cardiomyopathy with Ischemic Stroke is Minimally Explained by Atrial Fibrillation: The Atherosclerosis Risk in Communities (aric) Study

Abstract

Introduction: Atrial cardiomyopathy, characterized by abnormalities in left atrial (LA) size and function, is a risk factor for atrial fibrillation (AF) and ischemic stroke. We aimed to determine if 2D-echocardiographic (2DE) LA strain and volumetric parameters are independently associated with ischemic stroke and the extent to which AF mediates this risk in the ARIC study, a community-based cohort study. Methods: We included 4817 ARIC participants (mean age 75; 59% women; 22% Black) and who had 2DE in 2011-13. We evaluated LA volume index (maximum, minimum), LA emptying fraction (total, passive, active), LA strain (reservoir, conduit, contractile). Incident ischemic strokes (2013-2019) were physician adjudicated after review of medical records. AF was ascertained from hospitalization discharge codes and 2-week ambulatory rhythm monitoring in 2016-17. We used multivariable Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals (CI) of LA parameters for stroke and performed mediation analyses to quantify the indirect effect of AF in these associations. Results: After a median follow-up of 5.9 years, each SD increment in LA reservoir stain, LA conduit strain, LA contractile strain, total LA emptying fraction, and active LA emptying fraction was associated with a percent (95% CI) decrease in stroke risk of 27 (14-38), 19 (4-32), 17 (4-29), 19 (6-31), and 14 (1-26), respectively. Greater left atrial minimum, but not maximum volume index was associated with higher stroke risk. The proportion of these associations which was mediated by AF ranged from 3-36%. Our findings remained unchanged in sensitivity analysis excluding participants with AF and on anticoagulants. Conclusions: The associations of LA strain and volumetric parameters with stroke are minimally mediated by AF. Future research should determine whether LA strain and volumetric analysis can guide anticoagulation for stroke prevention in people independent of AF status.