Abnormal left ventricular energy metabolism in obese men with preserved systolic and diastolic functions is associated with insulin resistance

Abstract

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 (MR) techniques.

Research Design and Methods. We studied 81 healthy men (age range: 22-55 years, BMI range: 19-35 kg/m²) by means of cardiac MR imaging (MRI) and ³¹P-MR spectroscopy (MRS) 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 (PCr)/ATP ratio was reduced across increasing quartiles of 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 HOMA2 model); this relation was independent of age, BMI, blood pressure, wall mass, HDL-cholesterol, triglycerides, smoking habits and metabolic syndrome.

Conclusion. Abnormal LV energy metabolism was detectable in obese men in 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.