Background: Based on various epidemiological observations, it has been hypothesized that there is a "diabetic cardiomyopathy" strictly related to diabetes per se and probably due to an increase in the collagen content at the myocardial level, to microangiopathy or to complex alteration of myocardial metabolic pattern. Ultrasonic tissue characterization has recently been applied with different methodological approaches in order to identify early structural alterations of the myocardium.
Methods: We used two different methods of myocardial tissue characterization, i.e. integrated backscatter and videodensitometry, to analyze 26 type I diabetics without clinical symptoms, without hypertension or coronary artery disease, which were excluded on the basis of a negative exercise ECG, and in whom conventional echocardiographic parameters were normal. Seventeen healthy age- and sex-matched subjects were evaluated as the control group.
Results: Of the common left ventricular functional indexes, only E/A ratio (expression of global diastolic function) was lower in diabetics compared with controls (p < 0.01). The integrated backscatter index (IBI%) at the septum and posterior wall was significantly higher in diabetics as compared to controls, expressing an increased collagen content on a myocardial level. The cyclic variation index (%) of the mean gray level (videodensitometry) was significantly lower in diabetics in comparison with controls, both for the septum (p < 0.0001) and posterior wall (p < 0.002). This probably expresses an altered intrinsic myocardial contractility, due to an increase in myocardial collagen content and/or impairment of micro-circulatory function.
Conclusion: In agreement with previous studies, we found an altered behavior in myocardial tissue reflectivity in type I diabetics. The real significance of this finding in the "normal" heart is the subject of intense debate. One hypothesis is that these findings could be considered a very early index of a "diabetic cardiomyopathy".