Abstract 12120: Association of Physical Activity and Myocardial Fibrosis: The Multi-Ethnic Study of Atherosclerosis (MESA)

Introduction: Extracellular volume (ECV), native T1 time and late gadolinium enhancement (LGE) are markers of myocardial fibrosis (MF) by cardiac magnetic resonance imaging (CMR), and are associated with CV events, HF and death. Population studies on the association of physical activity (PA) and MF have not been published. Methods: MESA participants with data on Moderate and Vigorous PA (MET*min/week) at Exams 1, 2, 3 or 5, and ECV (%), T1 time (ms) and presence of LGE at Exam 5 were included. We constructed participant-specific trajectories of log-transformed PA levels using nonparametric B-splines based on best linear unbiased prediction. The area under the trajectory curve was used to estimate the 10-year PA level prior to Exam 5. We explored the associations of log-transformed PA at Exam 1 (PA 1 ), at Exam 5 (PA 5 ) and cumulative over 10 years (PA 1-5 ), with outcomes of interest (ECV, T1 time and LGE), using multivariable analysis. PA values were divided by their respective SD. Covariates included were demographic and lifestyle factors, CVD risk factors and CVD events. Results: A total of 2,682 participants were included (52% women, mean age 69 ± 9 years). PA 1 , PA 5 , and PA 1-5 were significantly greater in men (p<0.001 for all). PA 1 , PA 5 and PA 1-5 were not associated with ECV, T1 time or LGE in any model, for the entire cohort. Although interaction of PA 5 and PA 1-5 with sex was significant in the association with ECV, there was no significant association between PA and ECV in either men or women. Additionally, interaction of PA with sex was not significant in the association with either T1 time or LGE. Conclusions: In the MESA cohort, greater moderate and vigorous physical activity at baseline, at time of CMR, and cumulative over 10 years prior to CMR was not associated with ECV, native T1 time or LGE. Additionally, although interaction of PA with sex was significant in the association with ECV, there was no significant association between PA and ECV in either men or women.