Abstract P387: Associations of Abdominal Muscle Mass with Change in CAC Over Time Differ by Sex/Ethnic Group
Background: Body mass index (BMI) and other regional body composition measures are associated with subclinical and clinical cardiovascular disease (CVD); however, to date very little emphasis has been placed on examining the role of muscle mass in CVD. Loss of muscle mass may be particularly important in CVD and other chronic disease processes in older adults. Thus, we examine the association of abdominal muscle mass with coronary artery calcium (CAC) progression in a multi-ethnic sample of older adults.
Methods: From 2001-02 and then again approximately four years later, a sample of 452 white men and women, African-American (AA) women, and Filipina women, who were free of clinical CVD underwent computed tomography (CT) scans for CAC and abdominal body composition. Abdominal muscle measures were obtained at the 2001-02 exam using Medical Imaging Processing Analysis and Visualization (MIPAV) software, and included the psoas, paraspinal, rectus abdominus, and oblique muscles. Total muscle was obtained by summing the four muscle groups. CAC progression was modeled as progression versus not, using the Hokanson definition, and logistic regression for the analysis. Relative change in CAC was also examined as (ln((time 2 - time 1)/time 1)) using linear regression. Interactions of sex/ethnic group and muscle groups were examined. Models were adjusted for age, sex/ethnic group, BMI, smoking, physical activity, diabetes, hypertension, lipids and glucose.
Results: Mean age was 63±7 years; 33% of participants were white women, 27% white men, 20% AA women, and 20% Filipina women, and all women were postmenopausal. Approximately 78% of white men had CAC progression defined as a binary variable; 59% of white women, 65% of Filipina women and 37% of AA women had CAC progression. There were significant interactions of sex/ethnic group with total, paraspinal and oblique muscle for change in CAC over time (p-for-interactions 0.03, 0.03, and 0.001, respectively). Among Filipina women, each standard deviation (SD) greater total muscle was associated with a 26% (95% CI (-40%, -9%), p=0.005) reduced rate of change in CAC. In these same women, each SD higher paraspinal muscle and oblique muscle was associated with a 24% (-36%, -10%, p=0.002) and a 37% (-50%, -20%, p=0.0002) reduced rate of change in CAC, respectively. The other sex/ethnic groups did not have any significant associations of muscle with change in CAC. Total muscle or any of the four muscle groups were not associated with CAC progression defined as a binary variable, and there were no significant sex/ethnic interactions.
Conclusions: Among Filipina women, greater abdominal muscle mass is associated with a decreased rate of CAC change over time compared with the other sex/ethnic groups. Building and maintaining muscle as Filipina women age may be especially important for this group in reducing CVD outcomes.
- © 2013 by American Heart Association, Inc.