Abstract 17686: The Association Between Physical Activity Intensity and Left Atrial Size Among Healthy Adults: The Cooper Center Longitudinal Study

Abstract

Introduction: Increased left atrial (LA) volume has been proposed as a mechanism through which high levels of physical activity (PA) might increase the risk for atrial fibrillation (AF). However, the relationship between the intensity of PA and LA volume has not been previously reported. We hypothesized that vigorous activity would be more strongly associated with LA volume when compared to moderate PA. Methods: We included 1,641 healthy participants (age 55.6 years, 53.4% men) from the echocardiography substudy of the Cooper Center Longitudinal Study who were free of cardiovascular disease. PA was measured by self-report questionnaire that quantified the amount of moderate and vigorous PA performed in mins per week. LA volume was measured by 2D echocardiography using the biplane area-length method. The association between PA and LA volume indexed to body surface area was estimated using multivariable linear regression models with LA volume as the dependent variable and total, moderate, and vigorous activity (in min/per week) as the independent variables. Models were additionally adjusted for age, body mass index (BMI), hypertension, diabetes, and fitness. Results: Average levels of moderate, vigorous, and total PA in the study sample were 111, 103 and 191 min/week, respectively, with 68% of participants reporting some level of PA. As expected, higher levels of PA were associated with a lower BMI, lower blood pressure, and lower diabetes prevalence (p<.05 for all). In multivariable adjusted models, age, fitness, BMI and higher vigorous activity were associated with a larger LA size. However, there was no apparent association between moderate PA and LA size (see table). Conclusion: Higher vigorous but not moderate PA was associated with a larger LA size. These data suggest that lower intensity exercise prescriptions might be preferred in clinical circumstances marked by concern for AF risk.