Effect of cardiovascular autonomic neuropathy (CAN) on left ventricular function in normotensive type 1 diabetic patients: A study by pulsed wave tissue Doppler echocardiography

Abstract

Background and aim: Patients with diabetes mellitus are at increased risk for cardiovascular diseases. Cardiovascular autonomic neuropathy (CAN) is a serious complication of diabetes, as it can contribute in the pathogenesis of diabetic cardiomyopathy (DCM) and has been weakly linked with left ventricular diastolic dysfunction. Our aim was to investigate the effect of presence or absence of cardiovascular autonomic neuropathy (CAN) on systolic and diastolic LV function in normotensive type 1 diabetic patients by using both conventional and tissue Doppler echocardiography. Subjects and methods: Fifty two type 1 diabetic patients entered this study. They were divided into two groups. The first group included 24 patients with evidence of cardiovascular autonomic neuropathy. The second group included 28 patients without evidence of cardiovascular autonomic neuropathy. In addition to 18 healthy normal weights non diabetic subjects as a control group. Complete clinical examination, routine laboratory investigations, lipid profile, urinary albumin excretion, HbA1c and 12 leads ECG were done to all participants. Conventional and tissue Doppler indices of systolic and diastolic left ventricular function were recorded. Results: Heart rate was significantly higher in diabetic patients with CAN compared to both diabetic patients without CAN and normal control subjects (P < 0.001, <0.001, respectively). Glycemic control as assessed by HbA1c was more worse in diabetic patients with CAN compare to diabetic patients without CAN (P < 0.001). As regard conventional echo-Doppler, there were a significant difference in A wave velocity and E/A ratio in diabetic patients with or without CAN compared to control (P < 0.001, <0.001, <0.001, <0.001, respectively). Tissue Doppler indices show a significant difference at the lateral annular side in Em and Am velocity and Em/Am ratio in diabetic patients with or without CAN vs. control (P < 0.001, <0.001, <0.001, <0.05, <0.05, <0.01, respectively) and also, between diabetic patients with CAN vs. diabetic patients without CAN (P < 0.001, <0.05, <0.01, respectively). Also, tissue Doppler indices show a significant difference at the septal annular side in Em and Am velocity and Em/Am ratio in diabetic patients with or without CAN vs. control (P < 0.001, <0.001, <0.001, <0.01, <0.05, <0.05, respectively) and also, between diabetic patients with CAN vs. diabetic patients without CAN (P < 0.001, <0.05, <0.01, respectively). Contrary to that, no significant differences were found in LV systolic function parameters measured by either conventional or tissue Doppler imaging among the three groups. Conclusion: Our results demonstrated that, LV diastolic function was impaired in normotensive type 1 diabetic patients and, the presence of CAN is associated with more deterioration in diastolic function. Systolic function is seems to be unaffected. TDI should be the preferred modality in evaluation of LV function as it can detect minimal changes in diastolic function much earlier than conventional echo-Doppler.

Keywords

• Cardiovascular autonomic neuropathy (CAN)
• Left ventricular diastolic function
• Tissue Doppler imaging (TDI)