Abstract 4191: Abnormal Cardiac Energetics are Associated with Diastolic Dysfunction in Uncomplicated Obesity
Background: Abnormal cardiac high energy phosphate metabolism may lead to contractile dysfunction in heart failure. As the incidence of heart failure is increased in obesity, we have determined whether cardiac energy metabolism is abnormal in healthy, obese subjects.
Methods and Results: Cardiac phosphocreatine (PCr) to ATP ratios and function were measured using magnetic resonance spectroscopy and imaging, respectively, in 20 asymptomatic obese adults and 19 age- and sex-matched controls. Fasting plasma leptin, glucose, insulin, C-reactive protein, lipid and free fatty acid (FFA) concentrations were also measured. With a mean body mass index (BMI) of 31 kg/m2, the obese subjects had 16% lower cardiac PCr/ATP ratios and 54% higher fasting plasma FFA concentrations than the control subjects, who had a mean BMI of 24 kg/m2. Multivariate stepwise linear regression analysis demonstrated that plasma FFA concentrations (β −0.5, P = 0.001) and BMI (β −0.3, P = 0.03) were significant independent predictors of the cardiac PCr/ATP ratio (model adjusted R2 = 0.46). The peak filling rate, a measure of diastolic dysfunction, correlated with the cardiac PCr/ATP ratio (r = 0.42, P = 0.013).
Conclusions: Uncomplicated obesity is associated with decreased cardiac PCr/ATP ratios, diastolic dysfunction and increased plasma FFA concentrations, raising the possibility that abnormal cardiac high energy phosphate metabolism may contribute to the increased incidence of heart failure in obesity.