Early impairment of contractility reserve in patients with insulin resistance in comparison with healthy subjects

BACKGROUND: Insulin resistance (IR) is currently considered a crucial cardiovascular (CV) risk factor, which seems to play a dominant role in the evolution toward cardiac and vascular impairment. Early IR-induced cardiac dysfunction can be assessed by Doppler-derived myocardial systolic strain rate (SR) index, measured at baseline and after dobutamine stress echocardiography (DSE). METHODS: Thirty IR patients (HOMA-IR = 7 ± 5.2, age 52.6 ± 2.1 years), and 20 healthy, age and sex matched controls were studied. IR had been diagnosed in all patients in the 3 months preceding the study. Dobutamine echocardiography was performed in all subjects to exclude ischemic heart disease, and left ventricular contractile reserve (LVCR) was then assessed. LVCR was evaluated as an increase in the peak of an average longitudinal SR, measured in the basal and mid segments of 2 and 4 chamber ventricular walls. RESULTS: No significant differences between the 2 groups were revealed by baseline echocardiography. In contrast, after DSE a significant decrease of Delta SR was found in the IR group in comparison to the controls (0.54 ± 0.31 s⁻¹ vs 1.14 ± 0.45 s⁻¹; p < 0.0001). CONCLUSIONS: Our results show that IR, even if isolated and arising within a short time period, not only represents the initial phase of future diabetes, but may adversely affect heart function, as evidenced by the depressed LVCR. Our data strengthen the need for attention to be paid to IR state and for an early therapeutic approach.