Background: Obesity is an important contributor to many cardiovascular risk factors and has been associated with abnormalities in cardiac contractile function. Causes of impaired contractile function are not fully understood and may include an oversupply of substrates.
Objective: We tested the hypothesis that metabolic dysregulation may adversely influence cardiac function. Specifically, we examined the effects of plasma free fatty acids and insulin sensitivity on left ventricular function in patients with clinically severe obesity.
Design: We measured metabolic and cardiac variables in 64 obese patients [body mass index (BMI; in kg/m(2)) > 35], including 2-D complete echocardiogram with M-mode and tissue Doppler imaging, anthropometric measurements, and analysis of blood chemistries.
Results: The median (25th and 75th percentile) age and BMI were 46 y (36, 53 y) and 51.5 (42.5, 56.5), respectively. The prevalence of diabetes, hypertension, and insulin resistance were 38%, 53%, and 90%, respectively. Plasma free fatty acid (FFA) concentrations were elevated in the cohort. No association was observed between insulin sensitivity or anthropometric measurements and left ventricular contractile function. However, FFA concentration was independently associated with diastolic function (r = -0.33, P = 0.01), and 40% of the cohort showed age-adjusted diastolic impairment as measured by tissue Doppler imaging.
Conclusion: The negative association between FFA and diastolic function, in the setting of insulin resistance, suggests that excess FFA may exert a lipotoxic effect on the heart.