Background

A greater left ventricular mass (LVM) has been associated with incident cardiovascular events in cohort studies. The LVM has been shown to be associated with larger body mass index (BMI) or body surface area (BSA), which may partially explain the association between obesity and cardiovascular disease (CVD). However, despite the importance of cardiorespiratory fitness (CRF) to lower CVD, few studies have examined how CRF contributes to LVM within the context of obesity. The purpose of this investigation is to examine the cross-sectional association between LVM and CRF in adults who are overweight or obese.

Methods

Data were examined from sedentary adults (N=381; BMI: 32.4±3.8 kg/m2) prior to engaging in a behavioral weight loss program. All participants were evaluated for body composition using dual-energy x-ray absorptiometry (DXA), CRF from a graded exercise test, and LVM using cardiac magnetic resonance imaging (CMRI).

Results

Regression analysis was used with race, gender, age, and height were included in each model. Using stepwise regression, weight (kg, β=0.78, p<0.0001), percent body fat (β=-0.85, p<0.0001), and mean arterial pressure (β=0.36, p<0.0001), were significant predictors of LVM. In this model CRF expressed as absolute oxygen consumption (L/min, β=5.52, p=0.0102) was also a significant predictor of LVM. When further examined using relative oxygen consumption (ml/kg/min, β=0.44, p=0.0218) or time to termination on the exercise test (minutes, β=0.56, p=0.0374), CRF remained a significant predictor of LVM. When additional analyses were performed replacing percent body fat with BMI or BSA, similar results were observed.

Conclusions

When examining the association between obesity and risk for CVD it is important to consider the independent contribution of CRF to this relationship. Thus, interventions to treat obesity should focus on both weight reduction and improved CRF to have the greatest impact on reducing risk for CVD.Supported by: NIH (R01 HL103646)