Abstract 1134: Gender Differences in the Effect of Obesity on the Heart
Objectives: To determine if there are gender-related differences in myocardial blood flow (MBF), oxygen metabolism (MVO2), efficiency, glucose utilization (MGU), or fatty acid utilization (MFAU) between young, obese men and women.
Background: We have shown that obese, young women have higher MVO2, MFAU, and decreased efficiency and diastolic function compared with nonobese women. Whether there are similar changes in obese, young men is unknown.
Methods: In a prospective study, nondiabetic, nonhypertensive, young subjects (N=26) in the resting, fasted state (8 obese men [age 34±6yrs] , 18 weight- and age-matched women [33±7yrs]) underwent positron emission tomography (PET) imaging for quantification of MBF, MVO2, MGU, and MFAU. Plasma substrate, insulin levels, and cardiac structure and function (quantified using echocardiography) were measured during the PET. Tissue Doppler imaging quantified load-independent systolic (Sm) and diastolic (Em) function. Efficiency (Eff) = cardiac minute work/ MVO2. We quantified body and abdominal composition with dual-energy X-ray absorptiometry and magnetic resonance imaging.
Results: The men compared with the women had lower % body fat (32±4 v. 45±4%, p<.0001), higher triglycerides (215±71 v. 115±63mg/dL, p=.002), fasting glucose 5.4±0.3 v. 4.9±0.3, p=.0002), lower HDL (37±8 v. 52±12, p=.004), and trends toward higher systolic blood pressure (134±11 v. 124±13mmHg, p=.07), and more visceral fat (2933±772 v. 1759±1312cm3 p=.08). There was no difference in Sm, MGU, or MFAU.
Conclusions: Obese men have a worse metabolic profile, diastolic function, lower MBF, MVO2, and higher efficiency than age- and weight- matched obese women. These differrences do not appear to be the result of differences in exogenous fatty acid or glucose use. Further studies are needed to determine the mechanisms of these gender-related differences in the effects of obesity on the heart.