Abstract 14874: Low Cardiorespiratory Fitness is Associated with Smaller Heart Size, Increased Concentricity and Worsening Diastolic Function: The Cooper Center Echocardiographic Sub-Cohort

Abstract

Background: Higher physical activity is inversely associated with heart failure risk. However, the mechanism by which exercise lowers this risk is not fully understood. We sought to determine the cross-sectional association between measured cardiorespiratory fitness (CRF) and echocardiographic measures of left ventricular structure and function in a cohort of healthy adults.

Methods: We included 1,678 men and 1,247 women from the Cooper Center Longitudinal Study who received an echocardiogram at the Cooper Clinic from 1999 to 2011. CRF was measured by Balke protocol and categorized according to age specific quartiles with quartile 1 representing low CRF. The association between CRF and relative wall thickness (RWT), left ventricular end-diastolic diameter (LVEDD), left ventricular systolic function (LVEF), and E/e’ ratio were determined using multivariable linear regression with high CRF (quartile 4) as the referent.

Results: Participants were middle age (mean age 56) with a low prevalence of established CVD risk factors (15% obese; 4% DM; 28% HTN) and a normal CRF level (men: 11 METs; women: 9 METs). Compared to high CRF (quartile 4), low CRF was associated with a smaller LVEDD after adjustment for age, BMI, hypertension, and diabetes (β=-2.6, P<0.0001, and β=-2.4, P<0.001 in men and women, respectively). Similarly, low CRF was also associated with larger RWT (β=0.015, P=0.021; β=0.023, P=0.001) and with a greater E/e’ ratio (β=0.738, P=0.001; β=0.554, P=0.026). There was no association between low CRF and LVEF (P=NS). Compared to high CRF, lower CRF was also associated with a higher prevalence of diastolic dysfunction and concentric remodeling/hypertrophy (Figure).

Conclusions: Low CRF is associated with a higher prevalence of concentric remodeling/hypertrophy and diastolic dysfunction. These data suggest the hypothesis that exercise might lower heart failure risk through its effect on favorable cardiac remodeling and improved diastolic function.