Abstract 14520: Differences in Left Atrial Size and Function and Supraventricular Arrhythmias Between Blacks and Whites in the Atherosclerosis Risk in Communities (ARIC) Study: Implications for AF Pathogenesis

Abstract

Introduction: Black Americans have more atrial fibrillation (AF) risk factors but lower AF risk than whites. Left atrial (LA) enlargement, impaired LA function, frequent premature atrial contractions (PAC), and atrial tachycardia (AT) are risk factors for AF. Racial differences in LA size and function, PAC, or AT may exist that could explain the difference in AF risk. Hypothesis: Whites have higher PAC and AT frequency than blacks. Additionally, whites have larger LA size and lower LA function than blacks, which may contribute to the racial difference in AF. Methods: We included 1,623 ARIC participants free of AF who had 2D-echocardiograms at visit 5 (2011-2013) and wore a 2-week continuous heart monitor, the Zio ® XT Patch, at visit 6 (2016-2017). Weighted linear regression was used to analyze the association of race with LA size and function, as well as runs of AT per day and PAC per hour. Results: At visit 5, participants were 74 (4) years old, 58% were female, and 26% were black. AT runs were detected in 87% of blacks and 92% of whites, respectively (p=0.002). Among participants with >0 runs of AT per day (n=1480), blacks had 48% (95% CI: 21%-66%) fewer runs of AT per day than whites after adjustment for cardiovascular (CV) risk factors † . There was no significant difference in PAC frequency between blacks and whites. After adjusting for age and sex, blacks had greater LA size and lower LA function than whites; these differences attenuated after adjusting for CV risk factors (Table). Conclusion: Blacks have greater age and sex-adjusted abnormality in LA size and function than whites, likely due to higher prevalence of CV risk factors. Yet, blacks have lower propensity for AT. More research is needed to elucidate the mechanisms underlying the resistance to atrial arrhythmogenesis in blacks despite greater adverse LA remodeling.