QTc Interval and QT Dispersion Prolongation in NIDDM Patients with Diabetic Autonomic Neuropathy

Cho, Yong Kyun; Lee, Seung Won; Seo, Won Tae; Choi, Yoon Sang; Kang, Jin Ho; Lee, Man Ho; Lee, Sang Jong

Abstract

BACKGROUND: It has been reported that QTc interval and QT dispersion prolongation on 12 lead EKG reflects predictability and diagnosis of cardiovascular complications induced by autonomic nervous system abnormalities. We have investigated in NIDDM patients whether severity of cadiovascular autonomic neuropathy(CAN) evaluated by conventional standard cardiovascular autonomic function test is correlated with prolongation of QT, QTc interval and QT dispersion. In addition, whether these prolonagtion can reflect CAN and if any other clinical variables related to pralongatian exist.
METHODS
Eighty patients(39 male, 41 female) treated with oral hypoglycemic agents or insulin after diagnosis of NIDDM in our hospital were included in the study. These patients were devided into three groups (Group I, 13 subjects: No CAN, Group II, 20 subjects: Borderline CAN, Group III, 47 subjects: Definite CAN) according to the score of standard catdiovascular autonomic function test(Deep breathing test, Lying to standing test, Heart ration on Valsalva manuever, Postural BP drop test). The measured QT, QTc interval and QT disp rsion of eaeh diabetic group and control group were analyzed. RESULTS: l. Statistically significant prolongation of QT,QTc, QT dispersion was observed in NIDDM tients as compared with those of control group(p=0.015, 0,021, 0.001). 2. Severity of autonomic neuropathy has shown positive correlation with only prolongation of QT dispersion(p<0.05) in three diabetic subgroups. 3. Statistically significant difference was not ob::rved in HbAlc and BMI between each patients groups of NIDDM(p>0.05) but both HbAlc and BMI showed weak positive correlation with prologation of QT dispersion(r=0.262, r=0.267 repectively).
CONCLUSION
QTc interval and QT dispersion are considered easily accessible factors to predict and evaluate the degree of cardiovascular autonomic function abnormalities in NIDDM patients, yet further long term follow up and study in large group should be carried out to decide if these factor can predict and reflect severity of cardiovascular abnormalities such as ventricular arrhythmia, and sudden cardiac death. In additian, prolonged QT dispersion has shown weak positive correlation with both HbAlc and BMI and some other influential factors are suggested to play a role in autonomic neuropathy in NIDDM patients.