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 31P-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.