The Relation of QTc dispersion and Cardiovascular Autonomic Neuropathy in Patients with Type 2 Diabetes Mellitus

Yoon, Ji Sung; Won, Kyu Chang; Lee, Hyoung Woo

Abstract

BACKGROUND: The diabetic patients with cardiovascular autonomic neuropathy(CAN) have disturbance of repolarization due to sympathetic imbalance resulting in arrhythmogenesis, and finally leading to sudden death. QTc dispersion may provide regional variation in myocardial recovery time. Thus the hypothesis of this study was that QTc dispersion may be a useful tool in the assessment of arrhythmogenic potential in diabetic patients with CAN depending upon a severity of CAN. METHODS: Ninty-five patients with type 2 diabetes mellitus and 20 normal control subjects were studied. QTc interval and QTc dispersion was calculated from 12 lead ECG leads. QT dispersion was defined as difference between maximum and minimum QT interval and was corrected for heart rate using Bazzets formula. Cardiovascular autonomic neuropathy test(including resting heart rate, Valsalva maneuver, deep breathing, lying to standing, orthostatic hypotension) were assessed in all subjects. RESULTS: Among 95 diabetic patients, 43 patients (37%) had CAN. QTc interval and QT(QTc) dispersion were significantly greater in patients with CAN (p <0.05). There was no correlation between QTc interval and QTc dispersion. There was a statistically significant(r=0.48, p<0.001) correlation between systolic blood pressure response to standing and QTc dispersion. CONCLUSION: These results suggest that QTc dispersion may be an additional non-invasive diagnostic tool in the assessment of arrhythmogenic potential in diabetic patients with cardiovascular autonomic neuropathy.