RESUMO
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. 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. 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]. The present study showed that CABG does not affect QTd except in few patients with two-vessel coronary involvement