Abnormal Left Ventricular Energy Metabolism in Obese Men With Preserved Systolic and Diastolic Functions Is Associated With Insulin Resistance.

OBJECTIVE -- Perturbations in cardiac energy metabolism might represent early alterations in diabetes preceding functional and pathological changes. We evaluated left ventricular (LV) structure/geometry and function in relation to energy metabolism and cardiovascular risk factors in overweight/obese men using magnetic resonance techniques. RESEARCH DESIGN AND METHODS -- We studied 81 healthy men (aged 22-55 years, with BMI between 19 and 35 kg/m²) by means of cardiac magnetic resonance imaging and [sup 31]P-magnetic resonance spectroscopy in the resting and fasted conditions and stratified them in quartiles of BMI (cut offs: 23.2, 25.5 and 29.0 kg/m²). RESULTS -- LV mass increased across quartiles of BMI; meanwhile, the volumes did not differ. Parameters of LV systolic and diastolic function were not different among quartiles. The phosphocreatine-to-ATP ratio was reduced across increasing quartiles of mean ± SD BMI (2.25 ± 0.52, 1.89 ± 0.26, 1.99 ± 0.38, and 1.79 ± 0.29; P < 0.006) in association with insulin sensitivity (computer homeostasis model assessment 2 model); this relation was independent of age, BMI, blood pressure, wall mass, HDL cholesterol, triglycerides, smoking habits, and metabolic syndrome. CONCLUSIONS -- Abnormal LV energy metabolism was detectable in obese men in the presence of normal function, supporting the hypothesis that metabolic remodeling in insulin resistant states precedes functional and structural/geometrical remodeling of the heart regardless of the onset of overt hyperglycemia. [ABSTRACT FROM AUTHOR]