Background : Diabetic patients have an excess risk of dying from cardiovascular disease, QT interval variables on EKG were suggested as a non-invasive diagnostic tool in the assessment of diabetic cardiac autonomic neuropathy. It has been recently reported that QT interval variables could predict cardiac death in diabetic patients. We investigated whether QT interval variables also predicted ischemic heart disease in diabetic patients.
Methods : Among non-insulin dependent diabetic patients who were admitted to Hangang Sacred Heart Hospital since 1993, we selected study subjects who had no ischemic heart disease at the time of EKG and were follewed up for more than 4 years. Sex, age, duration of diabetes, blood pressure, smoking, HbAlc, diabetic, retinopathy, serum creatinine concentration at the time of EKG and QT interval variables(QT, QTc,QT dispersion, QTc dispersion) were analysed by regression analysis with ischemic heart disease as the sole end point.
Results : Out of total 118 patients, 21 patients developed ischemic heart disease during follow-up. Patients were followed up for a mean of 68 months. Sex,age, duration of diabetes, serum creatinine concentration and all QT variables were identified as the potentially important variables in univariate analysis. In Cox multivariate analysis with these variables, serum creatinine concentration and all QT variables were significant and independent predictors of ischemic heart disease in diabetic patients. Among QT variables, QTc dispersin outperformed all other predictors(risk ratio 8.132; confidence interval 3.908~16.921)
Conclusion : These results suggest that QT interval variables, especially QTc dispersion, could be a useful predictor of ischemic heart disease in diabetic patients and could be used as screening test to select diabetic patients for more extensive cardiac investigation.
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