Similar patterns of myocardial metabolism and perfusion in patients with type 2 diabetes and heart disease of ischaemic and non-ischaemic origin.

AIMS/HYPOTHESIS: Type 2 diabetes and insulin resistance are often associated with the co-occurrence of coronary atherosclerosis and cardiac dysfunction. The aim of this study was to define the independent relationships between left ventricular dysfunction or ischaemia and patterns of myocardial perfusion and metabolism in type 2 diabetes. METHODS: Twenty-four type 2 diabetic patients--12 with coronary artery disease (CAD) and preserved left ventricular function and 12 with non-ischaemic heart failure (HF)--were enrolled in a cross-sectional study. Positron emission tomography (PET) was used to assess myocardial blood flow (MBF) at rest, after pharmacological stress and under euglycaemic hyperinsulinaemia. Insulin-mediated myocardial glucose disposal was determined with 2-deoxy-2-[(18)F]fluoroglucose PET. RESULTS: There was no difference in myocardial glucose uptake (MGU) between the healthy myocardium of CAD patients and the dysfunctional myocardium of HF patients. MGU was strongly influenced by levels of systemic insulin resistance in both groups (CAD, r = 0.85, p = 0.005; HF, r = 0.77, p = 0.01). In HF patients, there was an inverse association between MGU and the coronary flow reserve (r = -0.434, p = 0.0115). A similar relationship was observed in non-ischaemic segments of CAD patients. Hyperinsulinaemia increased MBF to a similar extent in the non-ischaemic myocardial of CAD and HF patients. CONCLUSIONS/INTERPRETATION: In type 2 diabetes, similar metabolic and perfusion patterns can be detected in the non-ischaemic regions of CAD patients with normal cardiac function and in the dysfunctional non-ischaemic myocardium of HF patients. This suggests that insulin resistance, rather than diagnosis of ischaemia or left ventricular dysfunction, affects the metabolism and perfusion features of patients with type 2 diabetes.

Power spectrum analysis of circadian oscillations of heart rate variability in patients with left ventricular dysfunction.

OBJECTIVES: The physiological significance of diurnal fluctuations in heart rate variability (HRV) has not been established to a full extent. The aim of our investigation was to assess a new method of power spectrum analysis of circadian oscillations in HRV in patients with left ventricular systolic and diastolic dysfunction. METHODS: Holter ECG monitoring and echocardiography were performed in 101 patients with coronary artery disease and arterial hypertension: 55 patients with systolic left ventricular dysfunction (LVD) and 46 patients with diastolic LVD, and also in 32 subjects of the control group. The original method of HRV assessment was based on spectrum analysis of time series of consecutive 5-minute measures of standard deviations of mean RR intervals. RESULTS: The study revealed oscillations of HRV with a periodicity of 12 hours and 80-120 minutes. Their amplitude was highest in the control group and lowest in patients with systolic LVD. CONCLUSIONS: Power spectrum analysis of circadian oscillations of heart rate variability reveals information about the character of LVD. Regular oscillations of time domain indices of HRV were observed in the patients with LVD and in the control group; their amplitude is highest in the control group and lowest in systolic LVD.