Early Ventricular Dysfunction in Type II Diabetes: Role of Metabolic Unbalance

Abstract

Introduction: Diabetic cardiomyopathy is characterized by early myocardial systolic and diastolic impairment. Many studies have highlighted reduced contractile reserve in patients affected by Metabolic Syndrome (MS) and in the early stages of diabetes mellitus, however, it has not been confirmed by all the authors. A conclusive hypothesis on the basis of this early myocardial dysfunction needs to be ascertained. Methods: Forty patients: 20 (age 59 ± 7 years) with type II diabetes, diagnosed at least 5 years earlier and treated with insulin sensitizers, 20 with MS (WHO definition; age 57 ± 10 years), and 20 age- and sex-matched healthy controls were studied. MS patients with elevated insulin resistance (HOMA-IR >2.8), but no arterial hypertension with evidence of cardiac hypertrophy, were selected. In order to exclude ischemic heart disease and to evaluate left ventricle contractile reserve (LVCR), dobutamine echocardiography was performed on all patients. Results: No significant differences were shown by basal echocardiography between the 3 groups of subjects except for left ventricular mass, which was higher in diabetics than in MS and control subjects (78.8 ± 17.9 g/m2 vs. 64.3 ± 11.1 g/m2 and 58.2 ± 9.4 g/m2, respectively; p=ns and p<0.05). A significant decrease in delta longitudinal Strain Rate was noticed in the MS group compared to diabetics and controls (0.59 ± 0.29 s-1 vs. 1.07 ± 0.44 s-1 and 1.11 ± 0.43 s-1, respectively; p<0.001) Conclusion: The present findings show that insulin resistance is responsible for an initial myocardial impairment in patients with MS. This negative effect is not evident in the diabetic patients, probably due to the optimal treatment with insulin sensitizers. In our opinion, insulin resistance is able to modulate heart function, as testified by a depressed myocardial contractility reserve. Our data strengthen the need for the utmost attention to be paid to insulin resistance condition and to the opportunity of early therapeutic intervention.