Fitness in Young Adulthood and Long-Term Cardiac Structure and Function: The CARDIA Study

Objectives This study sought to evaluate the association between early-life cardiorespiratory fitness (CRF) and measures of left ventricular (LV) structure and function in midlife. Background Low CRF in midlife is associated with a higher risk of heart failure. However, the unique contributions of early-life CRF toward measures of LV structure and function in middle age are not known. Methods CARDIA (Coronary Artery Risk Development in Young Adults) study participants with a baseline maximal treadmill test and an echocardiogram at year 25 were included. Associations among baseline CRF, CRF change, and echocardiographic LV parameters (global longitudinal strain [GLS] and global circumferential strain, E/e′) were assessed using multivariable linear regression. Results The study included 3,433 participants. After adjustment for baseline demographic and clinical characteristics, lower baseline CRF was significantly associated with higher LV strain (standardized parameter estimate [Std β] = −0.06; p = 0.03 for GLS) and ratio of early transmitral flow velocity to early peak diastolic mitral annular velocity (E/e′) (Std β = −0.10; p = 0.0001 for lateral E/e′), findings suggesting impaired contractility and elevated diastolic filling pressure in midlife. After additional adjustment for cumulative cardiovascular risk factor burden observed over the follow-up period, the association of CRF with LV strain attenuated substantially (p = 0.36), whereas the association with diastolic filling pressure remained significant (Std β = −0.05; p = 0.02 for lateral E/e′). In a subgroup of participants with repeat CRF tests at year 20, greater decline in CRF was significantly associated with increased abnormalities in GLS (Std β = −0.05; p = 0.02) and higher diastolic filling pressure (Std β = −0.06; p = 0.006 for lateral E/e′) in middle age. Conclusions CRF in young adulthood and CRF change were associated with measures of LV systolic function and diastolic filling pressure in middle age. Low CRF–associated abnormalities in systolic function were related to the associated higher cardiovascular risk factor burden. In contrast, the inverse association between CRF and LV diastolic filling pressure was independent of cardiovascular risk factor burden.