Abstract 21237: Impact of Physical Fitness on Left Atrial Size in a Bi-racial Cohort of Young Adults: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Background: Left atrial enlargement (LAE) has been studied as a compensatory response to increased left heart filling pressures. While pathologic LAE is associated with abnormal diastole and poor outcomes, there is little known about the physiologic atrial remodeling that may occur with cardiorespiratory fitness.
Methods: We used Coronary Artery Risk Development In Young Adults (CARDIA), a bi-racial cohort balanced by race (black and white) and sex, age 18 to 30 years at enrollment, to study 4,049 young adults who completed a graded exercise treadmill test at year 0 and an echocardiogram to assess left atrial dimension (LAD) five years later. We used t-test to analyze the mean LAD in those above and below the sex-specific median maximum time exercised and used multiple linear regression to examine the independent association of maximum time exercised as a continuous variable with LAD, after adjustment for potential confounders such as heart rate and E/A ratio. We performed these analyses overall and within race-sex subgroups.
Results: We found that participants who were able to exercise longer than the median for their sex at year 0 had greater LAD on echocardiogram five years later (1.94 cm2 versus 1.91 cm2, p<0.001). Within race-sex groups, a significant increase in LAD among those with longer exercise duration was observed only among women (black women 1.99 cm2 versus 1.94 cm2, p=0.002; white women 1.98 cm2 versus 1.96 cm2, p=0.04). In all women, the relationship between exercise duration and increased LAD was independent of baseline age, diastolic blood pressure, resting heart rate, and E/A ratio (black women coefficient= 0.00012, p=0.04; white women coefficient= 0.00011, p=0.03).
Conclusion: In conclusion, young black and white women with greater cardiorespiratory fitness have greater LAD, findings not entirely explained by lower resting heart rates in these women. Further studies are necessary to determine which factors contribute independently to development of physiologic LAE.
- © 2010 by American Heart Association, Inc.