Background: QT dispersion (QT-D) an independent risk factor for sudden death due to arrhytmias indicates inhomogenous ventricular repolarization that increases in coronary artery disease (CAD) and diabetes mellitus. Early effects of coronary bypass surgery on QT-D in CAD patients having also diabetes mellitus were investigated in this study.

Methods: Fifty-four diabetic (Diabetic Group) and 50 non-diabetic (Control Group) coronary artery disease patients undergoing coronary bypass surgery that had no differences in age, sex, number of revascularized arteries and history of coronary events were included in the study. From 50 mm/sec ECG recordings of all patients QT min, QT max and QT-D values were measured preoperatively and 24 hours after coronary bypass operations. Corrected values (QTc min, QTc max and QTc-D) were obtained by Bazette formula.

Results: Preoperatively QT max, QTc max, QTc min and QTc-D values were found significantly greater in diabetic group. There were not any significant differences in QT min and QT-D between groups in the preoperative period. Comparison of postoperative values between groups revealed significant increase of QT max, QTc max, QT min and QT-D in diabetic group. But increase in QT, QTc min and QTc-D in diabetics was found statistically non-significant.

Conclusion: Diabetes mellitus in patients having regulated blood sugar was not found to be a factor that could increase arrhythmogenecity of heart in the early postoperative period of coronary bypass surgery.

Keywords : Diabetes mellitus, coronary bypass, QT dispersion, arrhythmia, electrical stability