Abstract MP10: Traditional Risk Factors for Atrial Fibrillation in Individuals with Normal Left Atrial Size: The Atherosclerosis Risk in Communities Study

Abstract

Background: Traditional risk factors for atrial fibrillation (AF) likely contribute to the pathogenesis of AF through their effects on left atrial (LA) enlargement. However, little is known about risk factors for AF in individuals with normal LA size. Hypothesis: We hypothesized that the risk factors for AF differ between individuals with normal and enlarged LA. Methods: LA diameter was measured by cardiac echocardiography in participants in the Atherosclerosis Risk in Communities (ARIC) study during 2011 - 13. AF was defined by ECGs and/or hospital discharge ICD-9 codes. Gender-specific cut points (3.9 cm for females and 4.1 cm for males were used to dichotomize the sample into normal and enlarged LA. Univariate and multivariate logistic regression models adjusting for age, gender, race, diabetes, hypertension, alcohol use (>1 drink/day), height, weight, coronary artery disease, heart failure, and exercise (>1 day per week) were used to evaluate risk factors for AF among ARIC participants with and without enlarged LA. Results: Of 5540 (mean age 75.6±5.2, women 58.6%) participants enlarged LA was present in 955 (16.2%). AF was prevalent in 3.9% of normal LA and 20% of enlarged LA participants. In multivariate analysis, alcohol use and exercise (>1 per week) were independently associated with AF in participants with normal sized LA (p<0.05)(table). Interaction terms of alcohol use, and exercise with LA size were statistically significant despite adjusting for age, gender, height, weight and race in the multivariate model. The population attributable risk of AF for alcohol use and lack of exercise were 5.5% and 6.4%, respectively. ` Conclusion: Many of the risk factors for AF are similar irrespective of the LA size. However, lack of exercise and alcohol drinking are associated with prevalent AF only in the normal sized LA group. More research is warranted to determine the potential benefits of interventions targeting these two modifiable risk factors in the setting of normal LA size.