Abnormal myocardial perfusion and contractile recruitment during exercise in type 1 diabetic patients

Background: No data are available on the relationship between myocardial perfusion and left ventricular (LV) function in type 1 diabetes mellitus (T1DM), which may constitute a factor explaining the progressive contractile dysfunction to the overt phase of diabetic cardiomyopathy. Hypothesis: This study was undertaken to test whether myocardial perfusion abnormalities are present at rest and during exercise and whether they are related to contractile dysfunction in T1DM. Methods: Twenty-two patients with T1DM, aged 32 ± 8.3 years, without macro-or microvascular complications, and 10 controls, aged 31 ± 3 years, were studied. Left ventricular function and myocardial perfusion were assessed by two-dimensional and myocardial contrast echocardiography at rest and during handgrip (HG). Results: Fourteen patients with T1DM showed a decline in LV ejectionfraction (LVEF) during HG (Group 1) while 8 had a normal response (Group 2). Both basal myocardial blood volume (MBV) and velocity ((3) were normal inT1DM. During exercise, MBV and (3 increased and were associated with an increase in myocardial blood flow (MBF) in controls. In T1DM, (3 did not change and MBV increased only in Group 2, while this increase was not observed in Group 1 (controls: 14.9 ±2.3 vs. Group 1:7.6± 1.6, p< 0.001; and vs. Group2:10.2± 2.8, p<0.001), (3(0.86±0.12vs.0.68±0.14, p<0.001;and vs. 0.67±0.15, p<0.001). A correlation between the ratio exercise MBF/resting MBF and LVEF at peak exercise in T1DM was observed (r=0.805, p< 0.001). Conclusions: A large proportion of patients with T1DM exhibit abnormalities in myocardial adaptable capacity to match an acute overload, which are related to a defective increase in myocardial perfusion.