INCREASED MYOCARDIAL-CONTRACTILITY IN YOUNG NEWLY DIAGNOSED TYPE-1 (INSULIN-DEPENDENT) DIABETICS FREE OF DIABETIC COMPLICATIONS - AN ECHOCARDIOGRAPHIC STUDY

One hundred and fifty-seven young cardiac asymptomatic type 1 diabetics and 54 control subjects were examined with M-mode echocardiography to elucidate the early changes in left ventricular systolic function (LVSF) in diabetes mellitus. Out of 157 diabetics a group of 40 newly diagnosed diabetics without diabetic complications was formed (retinopathy, nephropathy, autonomic neuropathy). They had ejection fraction (71.3 +/- 3.3%), fractional shortening (FS = 40.5 +/- 2.3%) and corrected mean velocity of circumferential fiber shortening (1.23 +/- 0.11 circ/s) significantly higher than those of the control subjects (65.7 +/- 3.0, 36.3 +/- 2.3, 1.08 +/- 0.09), but end-diastolic volume index (as preload, 72.9 +/- 11.7 ml/m), end-systolic meridional wall stress (MWSs, as afterload, 65.7 +/- 12.4 kdyn/cm2) and heart rate (HR = 72.8 +/- 10.0 bpm) were unchanged significantly compared to the control values (68.6 +/- 10.8, 70.9 +/- 15.0, 74.4 +/- 11.0). In 90% of the newly diagnosed diabetics the FS was above the 95% confidence limits of the control FS/MWSs relation, on the background of a significant difference (p < 0.001) in the frequency distribution between diabetics and control group (37%). These changes were probably due to increased myocardial contractility, rather than the changes in the loading condition since the other determinants of LVSF, such as preload, afterload and HR, were unchanged. In conclusion, our data impose the hypothesis that one of the early manifestations of the noncoronary diabetic cardiopathy is the increased myocardial contractility.