Effect of Coronary Artery Bypass Graft on QT interval Dispersion: A Measure of Inhomogeneity in Ventricular Repolarization

Background: The QT interval dispersion (QTd) has been described as the maximum minus minimum QT
intervals in simultaneously 12-lead electrocardiographic recording which reflect inhomogeneity in myocardial
repolarization.
Increased QTd has been illustrated in patients with a variety of cardiac diseases such as myocardial infarction
and left ventricular dysfunction and was suggested as a risk factor for development of ventricular arrhythmias
and sudden death. QTd may also be a prognostic factor in patients undergoing Coronary Artery Bypass Grafting
(CABG). The purpose of this study was to evaluate the influence of CABG on QTd in patients with coronary
artery disease.
Method: In this retrospective study we evaluated the effect of CABG on QTd in 79 consecutive patients with
coronary artery disease .Measurement of QTd was performed on ECGs taken before and 24 hours after operation.
Result: There was no significant QTd changes in post CABG patients compared with baseline QTd (0.06±0.04
vs. 0.06±0.03, P=0.18). In subgroups analysis, decrease in QTd was observed following CABG only in those
with two-vessel coronary involvement compared with baseline (0.05±0.04 SD seconds versus 0.07±0.02SD
seconds, P<0.05).
Conclusion:
The present study showed that CABG does not affect QTd except in few patients with two-vessel coronary
involvement.