Myocardial involvement during the early course of type 2 diabetes mellitus: usefulness of myocardial performance index

Abstract

To evaluate whether myocardial performance index detects a subclinical impairment of left ventricular systolic and diastolic function in patients with early stage of type 2 diabetes, without coronary artery disease, with or without hypertension. Furthermore, to evaluate whether some echocardiographic parameters relate to the metabolic control. Fourty-five consecutive male patients (mean age 52.5 years) with type 2 diabetes mellitus of recent onset (23 hypertensives and 22 normotensives) and 22 age matched healthy controls males were analysed. All participants had normal exercise ECG. All subjects underwent standard and Doppler echocardiography for the assessment of the isovolumic Doppler time interval and Doppler-derived myocardial performance index. In all diabetic patients a glycated haemoglobin test was also performed. No differences were observed in blood pressure, heart rate, and conventional echocardiographic parameters comparing the 2 subgroups of diabetic patients and the controls. Myocardial performance index was significantly higher in diabetic patients independently of the hypertension occurrence, compared to the controls (0.49 and 0.49 diabetic normotensives and hypertensives respectively vs. 0.39, p < 0.01). Myocardial performance index correlated to glycated haemoglobin significantly (r = 0.37, p < 0.01) in both diabetic subgroups. Thus, an early involvement of left ventricular performance was shown by myocardial performance index in patients with type 2 diabetes of recent onset without coronary artery disease, independently of the hypertension presence. These abnormalities can provide a feasible approach to detect a pre-clinical diabetic cardiomyopathy and could be useful for an indirect assessment of the metabolic control.

Figure 1

Flow Doppler at the mitral valve and at the LV outflow tract. Measurements of the time intervals of the Myocardial Performance Index (MPI). The interval "a" is measured from the end to the onset of mitral inflow waveform; the interval "b" is the left ventricular outflow velocity tracing (ET). The MPI was calculated as (a - b)/b.

Figure 2

Relationship between Myocardial Performance Index and glycated haemoglobin in all diabetic patients.