Early detection of diabetic cardiomyopathy: usefulness of tissue Doppler imaging

The aim of the study was to evaluate whether tissue Doppler imaging (TDI) detects a pre-clinical impairment of diastolic function in subjects with Type 2 diabetes with short duration of disease and normal cardiac function with conventional echocardiography (CE), and whether echocardiographic parameters are related to metabolic abnormalities.

We studied 40 non-obese, normotensive, uncomplicated Type 2 diabetic subjects with short duration of disease and 20 control subjects. All participants underwent both CE and TDI echocardiography. With TDI, early velocity (Ea), atrial velocity (Aa), their ratio (Ea/Aa) and systolic velocity (Sa) were measured at the lateral corner of mitral annulus. Glycosylated haemoglobin, fasting plasma glucose and insulin were determined and homeostasis model assessment (HOMA-IR), as an index of insulin resistance, was calculated.

Cardiac function with CE was similar in the two groups. Using TDI, diabetic subjects showed a lower Ea velocity (15.5+/-3.9 vs. 19.4+/-3.5 cm/s, P<0.0001), an increased Aa velocity (15.5+/-2.4 vs. 14.1+/-2.4 cm/s, P<0.05) and a reduced Ea/Aa ratio (1.00+/-0.2 vs. 1.39+/-0.3, P<0.0001), compared with control subjects. Linear regression analysis in the diabetic group showed that only HOMA-IR was negatively associated with Ea/Aa ratio (P=0.026). No significant association was observed with other metabolic variables.

An early stage of diabetic cardiomyopathy can be evidenced by TDI in Type 2 diabetic subjects even in the presence of a normal cardiac function with CE. This abnormality is associated with insulin resistance.