The risk for cardiovascular disease (CVD) and left ventricular dysfunction (LVD) is greater in HIV-infected people than in the general population, but the pathogenesis is unclear. Many HIV-infected people develop metabolic syndromes (HIV+MS) that include traditional CVD and LVD risk factors (dyslipidemia, insulin resistance, visceral adiposity) that are commonly observed in HIV-seronegative people and referred to as The Metabolic Syndrome.' We have reported that HIV+MS is characterized by an elevated free fatty acid rate of appearance (FFA Ra) in the circulation (ie, increased whole-body lipolytic rate), and lipid accumulation in skeletal muscle and liver. In HIV+MS, we hypothesize that the elevated FFA Ra increases FFA delivery, uptake and oxidation by the myocardium, but that myocardial FFA uptake eventually exceeds the ability of the heart to oxidize FFAs; intramyocardial lipid accumulation may result. We hypothesize that increased myocardial FFA uptake and oxidation are associated with structural changes in the left ventricle, and ventricular diastolic and systolic contractile dysfunction in HIV+MS. We propose to quantify whole-body FFA Ra (using 13C-palmitate and mass spectrometry), myocardial FFA delivery, uptake and oxidation (using radio-labeled palmitate and cardiac positron emission tomography (PET) imaging), and left ventricular (LV) structure, diastolic and systolic contractile function (using 2-D and tissue Doppler echocardiography) in 30 HIV+MS and 30 HIV-infected people without MS. We will compare these parameters between these 2 groups, and to exactly the same parameters quantified in HIV-seronegative people with and without The Metabolic Syndrome' who are currently being studied by co-investigators on this proposal at our Institution. For this project, HIV+MS is defined as HIV-infected women and men receiving stable anti-retroviral therapy and experiencing hypertriglyceridemia, low HDL-cholesterol levels, insulin resistance and visceral adiposity. The findings will identify similarities/differences in myocardial metabolism and LV contractile function between HIV+MS and The Metabolic Syndrome'. The findings may provide a mechanistic link between dysregulated whole-body and myocardial FFA metabolism that contributes to alterations in LV structure, contractile function and CVD. If so, treatments designed to reduce circulating FFA levels in HIV+MS, might effectively reduce CVD and LVD in HIV-infected people.
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